JP6724962B2 - Droplet ejector - Google Patents

Description

The present invention relates to a droplet discharge device such as a printer.

As an example of a droplet discharge device, ink (liquid) contained in a liquid supply source is supplied to a droplet discharge unit via a liquid supply path, and printing is performed by ejecting the ink from a nozzle of the droplet discharge unit onto a medium. There is an inkjet printer. Further, some of these printers include replaceable consumables such as a filter that collects foreign matters such as deposits and bubbles in the ink. Note that the consumable item is a product whose function changes to another state when used and its function deteriorates, and the degree of filter consumption is the degree of clogging. In such a printer, the degree of clogging of the filter is detected in order to determine when to replace the consumable filter (for example, Patent Document 1).

JP, 2010-228147, A

By the way, in Patent Document 1, in order to detect clogging of a filter, a flow rate sensor is provided on each of the upstream side and the downstream side of the filter, and a temperature sensor for detecting the temperature of the ink is provided. Therefore, in order to detect the clogging of the filter, it is necessary to provide a dedicated sensor, which increases the number of parts.

Note that these problems are not limited to printers equipped with filters, but are common to liquid droplet ejection devices equipped with consumables.
The present invention has been made in view of such circumstances, and an object thereof is to provide a droplet discharge device capable of detecting a malfunction of a consumable item while suppressing an increase in the number of parts.

Hereinafter, the means for solving the above problems and the operation effects thereof will be described.
A droplet discharge device that solves the above problem has a plurality of nozzles that discharge the liquid supplied from a liquid supply source through a liquid supply path as droplets, and discharges the droplets from the nozzles onto a medium. The droplet discharge unit for performing a recording process, the maintenance unit for performing a maintenance operation of the droplet discharge unit, and the discharge state detection unit capable of detecting the state in the pressure chamber communicating with the nozzle are provided. Section detects the state inside the pressure chamber before the maintenance operation and at least one of during the maintenance operation and after the maintenance operation, and based on a change in the state inside the pressure chamber due to the maintenance operation, the maintenance section It is possible to determine the malfunction of at least one of the functional units arranged in the liquid supply path.
A droplet discharge device that solves the above problem has a plurality of nozzles that discharge the liquid supplied from a liquid supply source through a liquid supply path as droplets, and discharges the droplets from the nozzles onto a medium. Detecting a vibration waveform of the pressure chamber that is vibrated by driving a droplet discharge unit that performs a recording process, a maintenance unit that performs a maintenance operation of the droplet discharge unit, and an actuator that vibrates a pressure chamber that communicates with the nozzle. A discharge state detecting unit capable of detecting a state in the pressure chamber, the discharge state detecting unit detects a vibration waveform of the pressure chamber before the maintenance operation, and during the maintenance operation and the maintenance operation. Detecting a vibration waveform of the pressure chamber at least one of after the operation, and based on a change in the state of the pressure chamber due to the maintenance operation, at least one of the maintenance unit and a functional unit arranged in the liquid supply path. Dysfunction can be determined.

Some droplet ejection devices include an ejection state detection unit that detects the state of the pressure chamber by driving an actuator to vibrate the pressure chamber and detect the vibration waveform of the pressure chamber. For example, the vibration waveform of the pressure chamber changes between when the pressure chamber and the nozzle are filled with liquid and when the pressure chamber and the nozzle contain bubbles. Therefore, it is determined based on the detected vibration waveform whether or not the droplet can be normally ejected from the nozzle. In addition, according to this configuration, the vibration waveform of the pressure chamber is detected before the maintenance operation, and the vibration waveform of the pressure chamber is detected at least during or after the maintenance operation. Then, by comparing the detected vibration waveforms, the change in the state inside the pressure chamber can be known. That is, when the change in the state of the pressure chamber and the change predicted from the maintenance operation are different, it is possible to determine the malfunction of the consumable item such as the maintenance section or the functional section. Therefore, by using the ejection state detection unit that originally detects the state of the pressure chamber for ejecting droplets, the malfunction of the consumable item can be detected while suppressing an increase in the number of parts.

In the droplet discharge device, when the change in the state of the pressure chamber is an increase of bubbles in the pressure chamber, the discharge state detection unit determines that at least one of the maintenance unit and the functional unit is malfunctioning. It is preferable to judge.

According to this configuration, when the change in the state inside the pressure chamber is an increase in bubbles, it can be inferred that the bubbles are mixed from the nozzle in accordance with the maintenance operation. Therefore, it can be determined that the maintenance unit that has performed the maintenance operation or the functional unit that acts on the liquid supplied as the liquid is consumed by the maintenance operation is malfunctioning.

In the droplet discharge device described above, the maintenance section may include a moisturizing cap having a cap section that contacts the droplet discharge section and closes a space facing the nozzle, and an atmosphere communication section that communicates the space with the atmosphere. Including the maintenance operation, the cap portion closes the space, and the discharge state detection portion detects the vibration waveform of the pressure chamber before the cap portion closes the space and closes the space. When the cap portion detects the vibration waveform of the pressure chamber after opening the space, and the change in the state of the pressure chamber is an increase of bubbles in the pressure chamber, the atmosphere communication unit is malfunctioning. It is preferable to judge.

For example, when the liquid is attached and solidified, the atmosphere communicating portion may fail to perform the function of communicating the space facing the nozzle and the space closed by the cap portion with the atmosphere. Then, if the space facing the nozzle is sealed with a moisturizing cap having an insufficient function of the atmosphere communicating portion, the pressure in the sealed space may increase and air may be mixed from the nozzle. On the other hand, according to this configuration, by detecting whether or not the bubbles increase before and after the cap portion comes into contact with the droplet discharge portion and seals the space facing the nozzle, the atmosphere communication portion is detected. Dysfunction can be determined.

In the droplet discharge device, the functional unit includes a filter arranged in the liquid supply path to collect foreign matter, and the maintenance unit discharges the liquid from the nozzle as the maintenance operation to detect the discharge state. It is preferable that the unit determines that the filter is clogged when the change in the state of the pressure chamber detected before and after the maintenance operation is an increase of bubbles in the pressure chamber.

When the filter is clogged, the flow rate, which is the amount of liquid that can pass through per unit time, decreases. Therefore, if the flow rate that can pass through the filter is less than the amount discharged from the nozzle per unit time, air may enter from the nozzle. In this respect, according to this configuration, it is possible to determine the malfunction of the filter for collecting the foreign matter based on the change in the state inside the pressure chamber before and after the droplet is ejected from the nozzle.

In the liquid droplet ejecting apparatus, the maintenance unit sets the ejection amount per unit time ejected from the nozzle in accordance with the maintenance operation to be the same as the maximum amount ejected per unit time from the nozzle during the recording process. It is preferable to discharge the liquid from the nozzle so that

According to this configuration, since the ejection amount ejected from the nozzle by the maintenance unit is the same as the maximum amount ejected from the nozzle during the recording process, it is possible to easily determine the malfunction of the filter.

In the above droplet discharge device, the maintenance section discharges the liquid from the nozzle by applying a negative pressure to the cap section that is in contact with the droplet discharge section and closes a space facing the nozzle. A maintenance pump that causes a negative pressure in the space closed as the maintenance operation, and the droplet discharge unit changes the state inside the pressure chamber detected before the maintenance operation and during the maintenance operation. It is preferable to judge that the function of the maintenance unit is normal.

When a negative pressure is applied to the space facing the nozzle and closed by the cap portion, the negative pressure is also applied to the pressure chamber via the nozzle. Furthermore, the vibration waveform of the pressure chamber changes depending on whether the negative pressure is applied to the pressure chamber or not. Therefore, according to this configuration, when the state in the pressure chamber before the maintenance operation in which the negative pressure is not applied and during the maintenance operation in which the negative pressure is applied changes, the negative pressure is applied to the pressure chamber. It can be determined that the maintenance section is functioning normally after being applied.

In the droplet discharge device, it is preferable that the droplet discharge unit discharges droplets from the nozzle by driving the actuator to vibrate the pressure chamber.
According to this configuration, the droplet can be ejected from the nozzle by the actuator that vibrates the pressure chamber in order to detect the state inside the pressure chamber. Therefore, the number of parts can be further reduced as compared with the case where each mechanism is provided separately.

In the droplet discharge device, when it is determined that at least one of the maintenance unit and the functional unit is malfunctioning based on a change in the state of the pressure chamber, it is preferable that the notification unit prompts replacement.

According to this configuration, since the notification unit prompts replacement, it is possible to replace the malfunctioning maintenance unit or functional unit at an appropriate timing.

FIG. 1 is a schematic diagram showing the configuration of an inkjet printer that is a type of droplet discharge device. FIG. 3 is a block diagram schematically showing a main part of the inkjet printer. FIG. 2 is a schematic sectional view of a head unit (inkjet head) in the inkjet printer shown in FIG. 1. FIG. 4 is an exploded perspective view showing the configuration of the head unit shown in FIG. 3. An example of a nozzle arrangement pattern of a nozzle plate of a head unit using four color inks. FIG. 4 is a state diagram showing each state when a drive signal is input in the III-III section of FIG. 3. FIG. 4 is a circuit diagram showing a simple vibration calculation model assuming residual vibration of the diaphragm of FIG. 3. 4 is a graph showing the relationship between experimental values and calculated values of residual vibration in the case of normal discharge of the diaphragm of FIG. 3. FIG. 4 is a conceptual diagram in the vicinity of a nozzle when air bubbles are mixed in the cavity of FIG. 3. 6 is a graph showing calculated values and experimental values of residual vibration in a state where ink droplets are no longer ejected due to the inclusion of bubbles in the cavities. FIG. 4 is a conceptual diagram of the vicinity of the nozzle when the ink near the nozzle of FIG. 3 is fixed by drying. 6 is a graph showing a calculated value and an experimental value of residual vibration in a dry and thickened state of ink near a nozzle. FIG. 4 is a conceptual diagram in the vicinity of a nozzle when paper dust adheres to the vicinity of the nozzle outlet of FIG. 3. The graph which shows the calculated value and experimental value of the residual vibration in the state where the paper dust adhered to the nozzle exit. The photograph which shows the state of the nozzle before and after the paper dust adheres to the vicinity of the nozzle. FIG. 3 is a schematic block diagram of an ejection abnormality detection unit. FIG. 4 is a conceptual diagram when the electrostatic actuator of FIG. 3 is a parallel plate capacitor. FIG. 4 is a circuit diagram of an oscillation circuit including a capacitor including the electrostatic actuator of FIG. 3. FIG. 17 is a circuit diagram of an F/V conversion circuit of the ejection abnormality detection unit shown in FIG. 16. 6 is a timing chart showing the timing of output signals of various parts based on the oscillation frequency output from the oscillator circuit. The figure for demonstrating the setting method of fixed time tr and t1. FIG. 17 is a circuit diagram showing a circuit configuration of the waveform shaping circuit of FIG. 16. The block diagram which shows the outline of the switching means of a drive circuit and a detection circuit. 6 is a flowchart showing ejection abnormality detection/determination processing. The flowchart which shows a residual vibration detection process. 6 is a flowchart showing a discharge abnormality determination process. An example of the timing of the ejection abnormality detection of a plurality of inkjet heads (when there is one ejection abnormality detection unit). An example of the timing of ejection abnormality detection of a plurality of inkjet heads (when the number of ejection abnormality detection means is the same as the number of inkjet heads). An example of ejection abnormality detection timings of a plurality of inkjet heads (when the number of ejection abnormality detection units is the same as the number of inkjet heads and ejection abnormality detection is performed when there is print data). An example of ejection abnormality detection timings of a plurality of inkjet heads (when the number of ejection abnormality detection units is the same as the number of inkjet heads and the ejection abnormality is detected by circulating each inkjet head). 28 is a flowchart showing the timing of ejection abnormality detection during the flushing operation of the inkjet printer shown in FIG. 27. 30 is a flowchart showing the timing of ejection abnormality detection during the flushing operation of the inkjet printer shown in FIGS. 28 and 29. 31 is a flowchart showing the timing of ejection abnormality detection during the flushing operation of the inkjet printer shown in FIG. 30. 30 is a flowchart showing the timing of ejection abnormality detection during the printing operation of the inkjet printer shown in FIGS. 28 and 29. 31 is a flowchart showing the timing of ejection abnormality detection during the printing operation of the inkjet printer shown in FIG. 30. FIG. 2 is a diagram showing a schematic structure (partially omitted) viewed from above the inkjet printer shown in FIG. 1. The figure which shows the positional relationship of the wiper and head unit which are shown in FIG. The figure which shows the relationship between a head unit, a cap, and a pump at the time of a pump suction process. The schematic diagram which shows the structure of the tube pump shown in FIG. 6 is a flowchart showing ejection abnormality recovery processing in the inkjet printer. 6A and 6B are diagrams for explaining another configuration example of a wiper (wiping unit), in which (a) shows a nozzle surface of a printing unit (head unit) and (b) shows a wiper. FIG. 42 is a view showing an operating state of the wiper shown in FIG. 41. The figure for demonstrating the other structural example of a pumping means. Sectional drawing which shows the outline of the other structural example of an inkjet head. Sectional drawing which shows the outline of the other structural example of an inkjet head. Sectional drawing which shows the outline of the other structural example of an inkjet head. Sectional drawing which shows the outline of the other structural example of an inkjet head. The perspective view which shows the structure of the head unit in 3rd Embodiment. FIG. 49 is a cross-sectional view of the head unit (inkjet head) shown in FIG. 48. The table which shows the printing mode in 4th Embodiment. Waveform of the highest image quality mode and high-speed image quality mode. Waveform of normal mode and high speed draft mode. The schematic diagram which shows the structure of the printer as a droplet discharge apparatus of 5th Embodiment. The top view which shows typically a part of printer of FIG. The schematic diagram which shows the structure of the printer as a droplet discharge apparatus of 6th Embodiment. 6 is a flowchart showing a filter clogging detection process. The flowchart which shows a discharge inspection process. The perspective view which shows the moisture retention mechanism of 7th Embodiment. The perspective view of a rigid member. The perspective view of a rigid member. Sectional drawing of a cap. The schematic diagram of the moisturizing mechanism located in a lower position. The schematic diagram of the moisturizing mechanism in the middle of rising. The schematic diagram of the moisturizing mechanism in a capping state. The schematic diagram of the moisture retention mechanism at the time of removing a moisture retention cap. The flowchart which shows the malfunction detection process of a moisturizing cap. The schematic diagram of the cavity during suction cleaning operation. The schematic diagram of the cavity before a suction cleaning operation.

Hereinafter, an embodiment of the droplet discharge device will be described with reference to the drawings.
The droplet discharge device is, for example, an inkjet printer that performs printing by discharging ink, which is an example of a liquid, onto a medium such as recording paper.

<First Embodiment>
FIG. 1 is a schematic diagram showing the configuration of an inkjet printer 1 which is a type of droplet discharge device according to the first embodiment. In the following description, the upper side in the vertical direction in FIG. 1 will be referred to as the “upper side”, and the lower side in the vertical direction will be referred to as the “lower side”. First, the configuration of the inkjet printer 1 will be described.

An inkjet printer 1 shown in FIG. 1 includes an apparatus main body 2, a tray 21 on which a recording sheet P is placed in the upper rear, a sheet ejection port 22 for ejecting the recording sheet P in the lower front, and an operation panel on the upper surface. 7 and are provided.

The operation panel 7 includes, for example, a liquid crystal display, an organic EL display, an LED lamp, and the like, and a display unit (not shown) that displays error messages and the like, and an operation unit (not shown) that includes various switches and the like. It has and. The display section of the operation panel 7 functions as a notification means.

Further, inside the apparatus main body 2, a printing device (printing device) 4 mainly including a reciprocating printing device (moving member) 3 and a paper feeding device for supplying/discharging a recording paper P to/from the printing device 4 are provided. It has a (droplet receiving material conveying means) 5 and a control section (control means) 6 for controlling the printing device 4 and the paper feeding device 5.

Under the control of the control unit 6, the paper feeding device 5 intermittently feeds the recording papers P one by one. The recording paper P passes near the lower part of the printing unit 3. At this time, the printing unit 3 reciprocates in a direction substantially orthogonal to the feeding direction of the recording paper P, and printing on the recording paper P is performed. That is, the reciprocating movement of the printing unit 3 and the intermittent feeding of the recording paper P serve as the main scanning and the sub-scanning in the printing, and the inkjet printing is performed.

The printing device 4 includes a printing unit 3, a carriage motor 41 serving as a drive source for moving (reciprocating) the printing unit 3 in the main scanning direction, and a reciprocating motion of the printing unit 3 in response to rotation of the carriage motor 41. And a moving mechanism 42.

The printing unit 3 includes a plurality of head units 35, an ink cartridge (I/C) 31 that supplies ink to each head unit 35, and a carriage 32 that mounts each head unit 35 and the ink cartridge 31. .. In the case of an ink jet printer that consumes a large amount of ink, the ink cartridge 31 is not mounted on the carriage 32 but installed at a different location, and the ink is supplied by communicating with the head unit 35 through a tube. (Not shown).

It should be noted that full-color printing is possible by using the ink cartridge 31 filled with four color inks of yellow, cyan, magenta, and black (black). In this case, the print unit 3 is provided with head units 35 (this configuration will be described later in detail) corresponding to each color. Here, in FIG. 1, four ink cartridges 31 corresponding to four color inks are shown, but the printing unit 3 includes ink cartridges of other colors such as light cyan, light magenta, dark yellow, and special color ink. It may be configured to further include 31.

The reciprocating mechanism 42 has a carriage guide shaft 422 whose both ends are supported by a frame (not shown), and a timing belt 421 extending in parallel with the carriage guide shaft 422.

The carriage 32 is reciprocally supported by the carriage guide shaft 422 of the reciprocating mechanism 42 and is fixed to a part of the timing belt 421.
When the timing belt 421 travels forward and backward through the pulley by the operation of the carriage motor 41, the printing means 3 reciprocates by being guided by the carriage guide shaft 422. Then, during this reciprocal movement, ink droplets are appropriately ejected from each inkjet head 100 of the head unit 35 in accordance with the image data to be printed (print data), and printing on the recording paper P is performed.

The sheet feeding device 5 has a sheet feeding motor 51 which is a drive source thereof, and a sheet feeding roller 52 which is rotated by the operation of the sheet feeding motor 51.
The paper feed roller 52 is composed of a driven roller 52 a and a drive roller 52 b which are vertically opposed to each other with the conveyance path (recording paper P) of the recording paper P therebetween, and the drive roller 52 b is connected to the paper feed motor 51. As a result, the paper feed roller 52 is configured to feed a large number of recording sheets P set on the tray 21 toward the printing device 4 one by one and to discharge the recording paper P from the printing device 4 one by one. Instead of the tray 21, a paper feed cassette for containing the recording paper P may be detachably mountable.

Further, the paper feed motor 51 also interlocks with the reciprocating operation of the printing unit 3 to feed the recording paper P according to the resolution of the image. The paper feeding operation and the paper feeding operation may be performed by different motors, or may be performed by the same motor by a component that switches torque transmission such as an electromagnetic clutch.

The control unit 6 controls the printing device 4, the paper feeding device 5, and the like based on print data input from a host computer 8 such as a personal computer (PC) or a digital camera (DC), and thereby the recording paper P. The print processing is performed on. In addition, the control unit 6 causes the display unit of the operation panel 7 to display an error message or the like, or turns on/blinks the LED lamp or the like, and performs a corresponding process based on the depression signals of various switches input from the operation unit. Is executed by each section. Further, the control unit 6 may transfer information such as an error message and discharge abnormality to the host computer 8 as needed.

As shown in FIG. 2, the inkjet printer 1 drives and controls an interface (IF) 9 that receives print data and the like input from a host computer 8, a control unit 6, a carriage motor 41, and a carriage motor 41. A carriage motor driver 43, a paper feed motor 51, a paper feed motor driver 53 that drives and controls the paper feed motor 51, a head unit 35, a head driver 33 that drives and controls the head unit 35, and an ejection abnormality detection unit 10. The recovery means 24 and the operation panel 7 are provided. The details of the ejection abnormality detection unit 10, the recovery unit 24, and the head driver 33 will be described later.

In FIG. 2, the control unit 6 includes a CPU (Central Processing Unit) 61 that executes various processes such as a printing process and an ejection abnormality detection process, and print data that is input from the host computer 8 via the IF 9 as data (not shown). An EEPROM (Electrically Erasable Programmable Read-Only Memory) (storage means) 62, which is a type of non-volatile semiconductor memory that is stored in the storage area, and temporarily stores various data when executing an ejection abnormality detection process described later. Or a RAM (Random Access Memory) 63 for temporarily expanding an application program such as print processing, and a PROM 64 which is a kind of non-volatile semiconductor memory for storing a control program for controlling each unit. The components of the control unit 6 are electrically connected via a bus (not shown).

As described above, the printing unit 3 includes the plurality of head units 35 corresponding to each color ink. Further, each head unit 35 includes a plurality of nozzles 110 and electrostatic actuators 120 respectively corresponding to the nozzles 110. That is, the head unit 35 is configured to include a plurality of inkjet heads 100 (droplet ejection heads) each having a set of nozzles 110 and an electrostatic actuator 120. The head driver 33 is composed of a drive circuit 18 that drives the electrostatic actuator 120 of each inkjet head 100 to control the ink ejection timing, and a switching unit 23 (see FIG. 16). The configuration of the electrostatic actuator 120 will be described later.

Further, although not shown, various sensors, which are capable of detecting the ink remaining amount of the ink cartridge 31, the position of the printing unit 3, the printing environment such as temperature and humidity, etc., are electrically connected to the control unit 6, respectively. ing.

When the control unit 6 obtains the print data from the host computer 8 via the IF 9, the control unit 6 stores the print data in the EEPROM 62. Then, the CPU 61 executes a predetermined process on the print data, and outputs a drive signal to the drivers 33, 43, 53 based on the process data and the input data from various sensors. When these drive signals are input via the respective drivers 33, 43, 53, the plurality of electrostatic actuators 120 of the head unit 35, the carriage motor 41 of the printing device 4 and the paper feeding device 5 respectively operate. As a result, the printing process is performed on the recording paper P.

Next, the structure of each head unit 35 in the printing unit 3 will be described. 3 is a schematic cross-sectional view of the head unit 35 (ink jet head 100) shown in FIG. 1, and FIG. 4 is an exploded perspective view showing a schematic configuration of the head unit 35 corresponding to one color ink. FIG. 5 is a plan view showing an example of the nozzle surface of the printing unit 3 to which the head unit 35 shown in FIGS. 3 and 4 is applied. It should be noted that FIGS. 3 and 4 are shown upside down from the state in which they are normally used.

As shown in FIG. 3, the head unit 35 is connected to the ink cartridge 31 via the ink intake port 131, the damper chamber 130, and the ink supply tube 311. Here, the damper chamber 130 includes a damper 132 made of rubber. The damper chamber 130 can absorb the fluctuation of the ink and the change of the ink pressure when the carriage 32 reciprocates, and thus a predetermined amount of ink can be stably supplied to the head unit 35.

Further, in the head unit 35, the silicon substrate 140 is sandwiched, and the nozzle plate 150 also made of silicon is laminated on the upper side, and the borosilicate glass substrate (glass substrate) 160 having a thermal expansion coefficient close to that of silicon is laminated on the lower side. It has a three-layer structure. In the central silicon substrate 140, a plurality of independent cavities (pressure chambers) 141 (7 cavities are shown in FIG. 4), one reservoir (common ink chamber) 143, and this reservoir 143 in each cavity 141. Grooves that function as ink supply ports (orifices) 142 that communicate with each other are formed. Each groove can be formed, for example, by performing an etching process on the surface of the silicon substrate 140. The nozzle plate 150, the silicon substrate 140, and the glass substrate 160 are joined in this order, and each cavity 141, reservoir 143, and each ink supply port 142 is defined.

Each of these cavities 141 is formed in a strip shape (rectangular parallelepiped shape), and its volume can be changed by vibration (displacement) of a vibration plate 121 described later. Due to this volume change, ink (liquid material) is discharged from the nozzle 110. It is configured to eject. Nozzles 110 are formed on the nozzle plate 150 at positions corresponding to the tip end side of each cavity 141, and these nozzles communicate with each cavity 141. Further, an ink intake port 131 communicating with the reservoir 143 is formed in the portion of the glass substrate 160 where the reservoir 143 is located. Ink is supplied from the ink cartridge 31 to the reservoir 143 through the ink supply tube 311, the damper chamber 130, the ink intake port 131. The ink supplied to the reservoir 143 is supplied to each independent cavity 141 through each ink supply port 142. Each cavity 141 is defined by the nozzle plate 150, the side wall (partition wall) 144, and the bottom wall 121.

Each of the independent cavities 141 has a thin bottom wall 121, and the bottom wall 121 is elastically deformable (elastically displaced) in the out-of-plane direction (thickness direction), that is, in the vertical direction in FIG. It is configured to function as a diaphragm (diaphragm). Therefore, the portion of the bottom wall 121 may be referred to as a diaphragm 121 for the convenience of the following description (that is, the reference numeral 121 will be used for both the "bottom wall" and the "vibration plate" hereinafter). ).

On the surface of the glass substrate 160 on the silicon substrate 140 side, shallow recesses 161 are formed at positions corresponding to the respective cavities 141 of the silicon substrate 140. Therefore, the bottom wall 121 of each cavity 141 faces the surface of the facing wall 162 of the glass substrate 160 in which the recess 161 is formed, with a predetermined gap. That is, there is a gap having a predetermined thickness (for example, about 0.2 μm) between the bottom wall 121 of the cavity 141 and the segment electrode 122 described later. The recess 161 can be formed by etching, for example.

Here, the bottom wall (vibration plate) 121 of each cavity 141 constitutes a part of the common electrode 124 on the side of each cavity 141 for accumulating electric charge by the drive signal supplied from the head driver 33. That is, the vibrating plate 121 of each cavity 141 also serves as one of the counter electrodes (counter electrodes of the capacitors) of the corresponding electrostatic actuator 120 described later. Then, segment electrodes 122, which are electrodes facing the common electrode 124, are formed on the surface of the recess 161 of the glass substrate 160 so as to face the bottom wall 121 of each cavity 141. Further, as shown in FIG. 3, the surface of the bottom wall 121 of each cavity 141 is covered with an insulating layer 123 made of a silicon oxide film (SiO ₂ ). As described above, the bottom wall 121 of each cavity 141, that is, the vibration plate 121 and each segment electrode 122 corresponding to the bottom wall 121 of the cavity 141 are formed on the insulating layer 123 formed on the lower surface of the bottom wall 121 of the cavity 141 in FIG. A counter electrode (counter electrode of the capacitor) is formed (configured) through the gap and the void in the recess 161. Therefore, the diaphragm 121, the segment electrodes 122, and the insulating layer 123 and the gap therebetween form a main part of the electrostatic actuator 120.

As shown in FIG. 3, the head driver 33 including the drive circuit 18 for applying a drive voltage between these counter electrodes responds to a print signal (print data) input from the control unit 6 in response to these signals. Charge and discharge between the counter electrodes. One output terminal of the head driver (voltage applying means) 33 is connected to each segment electrode 122, and the other output terminal is connected to an input terminal 124a of a common electrode 124 formed on the silicon substrate 140. Since impurities are injected into the silicon substrate 140 and the silicon substrate 140 itself has conductivity, a voltage can be supplied from the input terminal 124a of the common electrode 124 to the common electrode 124 of the bottom wall 121. Further, for example, a thin film of a conductive material such as gold or copper may be formed on one surface of the silicon substrate 140. As a result, a voltage (charge) can be supplied (efficiently) to the common electrode 124 with low electric resistance. This thin film may be formed by, for example, vapor deposition or sputtering. Here, in this embodiment, for example, since the silicon substrate 140 and the glass substrate 160 are bonded (bonded) by anodic bonding, the conductive film used as an electrode in the anodic bonding is formed on the flow channel forming surface side of the silicon substrate 140 (see FIG. It is formed on the upper side of the silicon substrate 140 shown in FIG. Then, this conductive film is used as it is as the input terminal 124a of the common electrode 124. Note that, for example, the input terminal 124a of the common electrode 124 may be omitted, and the bonding method between the silicon substrate 140 and the glass substrate 160 is not limited to anodic bonding.

As shown in FIG. 4, the head unit 35 includes a nozzle plate 150 in which a plurality of nozzles 110 are formed, a plurality of cavities 141, a plurality of ink supply ports 142, and a silicon substrate (ink chamber) in which one reservoir 143 is formed. Substrate 140 and an insulating layer 123, which are housed in a base 170 including a glass substrate 160. The base 170 is made of, for example, various resin materials or various metal materials, and the silicon substrate 140 is fixed and supported on the base 170.

Note that the nozzles 110 formed on the nozzle plate 150 are linearly arranged substantially parallel to the reservoir 143 for the sake of simplicity in FIG. 4, but the arrangement pattern of the nozzles is not limited to this configuration, and is generally Are staggered and arranged, for example, like the nozzle arrangement pattern shown in FIG. The pitch between the nozzles 110 can be appropriately set according to the print resolution (dpi: Dot Per Inch). Note that FIG. 5 shows an arrangement pattern of the nozzles 110 when four color inks (ink cartridges 31) are applied.

FIG. 6 shows each state of the III-III section of FIG. 3 when a drive signal is input. When a driving voltage is applied between the counter electrodes from the head driver 33, a Coulomb force is generated between the counter electrodes, and the bottom wall (vibration plate) 121 is different from the initial state (FIG. 6A) in the segment electrode. It bends to the 122 side, and the volume of the cavity 141 increases (FIG. 6B). In this state, when the electric charge between the opposing electrodes is rapidly discharged by the control of the head driver 33, the diaphragm 121 is restored upward in the figure by its elastic restoring force and exceeds the position of the diaphragm 121 in the initial state. And the volume of the cavity 141 is rapidly contracted (FIG. 6C). At this time, due to the compression pressure generated in the cavity 141, a part of the ink (liquid material) filling the cavity 141 is ejected as an ink droplet from the nozzle 110 communicating with the cavity 141.

The diaphragm 121 of each cavity 141 is attenuated by this series of operations (ink ejection operation by the drive signal of the head driver 33) until the next drive signal (drive voltage) is input and ink droplets are ejected again. It is vibrating. Hereinafter, this damped vibration is also referred to as residual vibration. The residual vibration of the diaphragm 121 is determined by the acoustic resistance r due to the shape of the nozzle 110 or the ink supply port 142, the ink viscosity, etc., the inertance m due to the weight of the ink in the flow path, and the compliance Cm of the diaphragm 121. It is assumed to have a natural vibration frequency.

A calculation model of the residual vibration of the diaphragm 121 based on the above assumption will be described. FIG. 7 is a circuit diagram showing a simple vibration calculation model assuming residual vibration of the diaphragm 121. As described above, the calculation model of the residual vibration of the diaphragm 121 can be represented by the sound pressure P, the inertance m, the compliance Cm, and the acoustic resistance r described above. Then, when the step response when the sound pressure P is applied to the circuit of FIG. 7 is calculated for the volume velocity u, the following equation is obtained.

The calculation result obtained from this equation is compared with the experimental result in the experiment of the residual vibration of the vibration plate 121 after the ejection of the ink droplet, which is separately performed. FIG. 8 is a graph showing the relationship between the experimental value and the calculated value of the residual vibration of the diaphragm 121. As can be seen from the graph shown in FIG. 8, the two waveforms of the experimental value and the calculated value are almost in agreement.

Now, in each of the inkjet heads 100 of the head unit 35, there may be a phenomenon in which an ink droplet is not normally ejected from the nozzle 110, that is, an ejection abnormality of a droplet occurs even though the ejection operation as described above is performed. As described below, the causes of the ejection abnormality are (1) mixing of air bubbles into the cavity 141, (2) drying/thickening (adhesion) of ink near the nozzle 110, and (3) nozzle 110. Adhesion of paper powder near the outlet may be mentioned.

When this ejection abnormality occurs, as a result, typically, the droplet is not ejected from the nozzle 110, that is, the ejection failure phenomenon of the droplet appears. In that case, in the image printed (drawn) on the recording paper P. Pixel missing dots occur. Further, in the case of an ejection abnormality, even if a droplet is ejected from the nozzle 110, the amount of the droplet is too small, or the flight direction (trajectory) of the droplet is deviated, so that the droplet does not land properly. , After all, it appears as missing pixels. For this reason, in the following description, the abnormal ejection of the droplet may be simply referred to as “dot omission”.

In the following, based on the comparison result shown in FIG. 8, the vibrating plate 121 remains depending on the cause of the dot omission (ejection abnormality) phenomenon (droplet non-ejection phenomenon) that occurs in the nozzle 110 of the inkjet head 100 during the printing process. The values of the acoustic resistance r and/or the inertance m are adjusted so that the calculated value of the vibration and the experimental value match (generally match).

First, consideration will be given to the inclusion of air bubbles in the cavity 141, which is one cause of dot omission. FIG. 9 is a conceptual diagram of the vicinity of the nozzle 110 when the bubble B is mixed in the cavity 141 of FIG. As shown in FIG. 9, the generated bubble B is assumed to be generated and attached to the wall surface of the cavity 141 (in FIG. 9, as an example of the attachment position of the bubble B, the bubble B is near the nozzle 110). Shows the case where they are attached).

As described above, when the bubbles B are mixed in the cavity 141, it is considered that the total weight of the ink filling the cavity 141 is reduced and the inertance m is reduced. Moreover, since the bubble B is attached to the wall surface of the cavity 141, it is considered that the diameter of the nozzle 110 is increased by the size of the bubble B and the acoustic resistance r is reduced.

Therefore, as compared with the case of FIG. 8 in which the ink is normally ejected, both the acoustic resistance r and the inertance m are set to be small, and by matching with the experimental value of the residual vibration when bubbles are mixed, as shown in FIG. The result (graph) was obtained. As can be seen from the graphs of FIGS. 8 and 10, when bubbles are mixed in the cavity 141, a characteristic residual vibration waveform having a higher frequency than that in normal ejection is obtained. It can be also confirmed that the attenuation rate of the amplitude of the residual vibration is reduced due to the decrease in the acoustic resistance r, etc., and the amplitude of the residual vibration is slowly decreased.

Next, the ink drying (fixing, thickening) in the vicinity of the nozzle 110, which is another cause of missing dots, will be examined. FIG. 11 is a conceptual diagram of the vicinity of the nozzle 110 when the ink near the nozzle 110 of FIG. 3 is fixed by drying. As shown in FIG. 11, when the ink in the vicinity of the nozzle 110 is dried and fixed, the ink in the cavity 141 is in a state of being trapped in the cavity 141. As described above, when the ink near the nozzle 110 is dried and thickened, the acoustic resistance r is considered to increase.

Therefore, by setting the acoustic resistance r to a large value and matching with the experimental value of the residual vibration at the time of ink dry fixation (thickening) in the vicinity of the nozzle 110, compared with the case of FIG. 8 in which the ink is normally ejected, The result (graph) as shown in FIG. 12 was obtained. In the experimental values shown in FIG. 12, the head unit 35 was left without a cap (not shown) for several days, and the ink in the vicinity of the nozzle 110 was dried and thickened, so that the ink could not be ejected ( This is a measurement of the residual vibration of the vibration plate 121 in the state where the ink is fixed). As can be seen from the graphs of FIGS. 8 and 12, when the ink near the nozzle 110 is fixed due to drying, the frequency becomes extremely lower than that during normal ejection, and the residual vibration is a characteristic residual vibration that is excessively damped. The waveform is obtained. This is because when the vibrating plate 121 is drawn downward in FIG. 3 to eject ink droplets, ink flows from the reservoir 143 into the cavity 141 and then the vibrating plate 121 moves upward in FIG. This is because the vibrating plate 121 cannot rapidly vibrate (because it is overdamped) because there is no escape path for the ink in the cavity 141.

Next, the paper dust adhesion near the outlet of the nozzle 110, which is another cause of dot omission, will be examined. FIG. 13 is a conceptual diagram of the vicinity of the nozzle 110 when paper dust adheres to the vicinity of the outlet of the nozzle 110 of FIG. As shown in FIG. 13, when the paper dust adheres to the vicinity of the outlet of the nozzle 110, the ink exudes from the inside of the cavity 141 through the paper dust, and the ink cannot be ejected from the nozzle 110. As described above, when the paper dust adheres to the vicinity of the outlet of the nozzle 110 and the ink oozes out from the nozzle 110, the ink in the cavity 141 and the oozing-out ink when viewed from the vibrating plate 121 increases more than in the normal state. Therefore, it is considered that the inertance m increases. Moreover, it is considered that the acoustic resistance r is increased by the fibers of the paper powder attached near the outlet of the nozzle 110.

Therefore, in comparison with the case of FIG. 8 in which the ink is normally ejected, both the inertance m and the acoustic resistance r are set to a large value to match the experimental value of the residual vibration when the paper dust adheres to the vicinity of the outlet of the nozzle 110. As a result, the result (graph) shown in FIG. 14 was obtained. As can be seen from the graphs of FIGS. 8 and 14, when the paper dust adheres to the vicinity of the outlet of the nozzle 110, a characteristic residual vibration waveform whose frequency is lower than that during normal ejection is obtained (here, the paper It can also be seen from the graphs of FIGS. 12 and 14 that the frequency of residual vibration is higher in the case of powder adhesion than in the case of ink drying). Note that FIG. 15 is a photograph showing the state of the nozzle 110 before and after the paper powder is attached. When paper dust adheres to the vicinity of the outlet of the nozzle 110, a state in which ink oozes out along the paper dust can be found from FIG. 15B.

Here, both when the ink near the nozzle 110 is dried and thickened and when the paper dust is attached near the outlet of the nozzle 110, the damping vibration is smaller than that when the ink droplet is normally ejected. The frequency is low. In order to identify the cause of these two missing dots (ink non-ejection: ejection abnormality) from the waveform of the residual vibration of the vibration plate 121, for example, comparison is made with a predetermined threshold value in the frequency, period, or phase of the damping vibration. Alternatively, it can be specified from the damping rate of the periodic change or the amplitude change of the residual vibration (damped vibration). In this way, the ejection abnormality of each inkjet head 100 can be detected by the change of the residual vibration of the vibration plate 121 when the ink droplets are ejected from the nozzles 110 of each inkjet head 100, in particular, by the change of the frequency thereof. You can Further, by comparing the frequency of the residual vibration in that case with the frequency of the residual vibration during normal ejection, it is possible to identify the cause of the ejection abnormality.

Next, the ejection abnormality detecting means 10 will be described. FIG. 16 is a schematic block diagram of the discharge abnormality detection means 10 shown in FIG. As shown in FIG. 16, the discharge abnormality detecting means 10 includes a residual vibration detecting means 16 including an oscillation circuit 11, an F/V converting circuit 12, and a waveform shaping circuit 15, and the residual vibration detecting means 16. Measuring means 17 for measuring the cycle, amplitude, etc. from the residual vibration waveform data detected by the measuring means 17, and judging means 20 for judging an ejection abnormality of the inkjet head 100 based on the cycle, etc. measured by the measuring means 17. There is. In the ejection abnormality detection means 10, the residual vibration detection means 16 causes the oscillation circuit 11 to oscillate based on the residual vibration of the diaphragm 121 of the electrostatic actuator 120, and the F/V conversion circuit 12 and the waveform shaping circuit are oscillated from the oscillation frequency. At 15, a vibration waveform is formed and detected. Then, the measuring unit 17 measures the period of residual vibration based on the detected vibration waveform, and the determining unit 20 determines each period of the head unit 35 in the printing unit 3 based on the measured period of residual vibration. The ejection abnormality of each inkjet head 100 included in is detected and determined. Hereinafter, each component of the ejection abnormality detecting means 10 will be described.

First, a method of using the oscillation circuit 11 to detect the frequency (frequency) of the residual vibration of the diaphragm 121 of the electrostatic actuator 120 will be described. FIG. 17 is a conceptual diagram when the electrostatic actuator 120 of FIG. 3 is a parallel plate capacitor, and FIG. 18 is a circuit diagram of the oscillation circuit 11 including the capacitor configured of the electrostatic actuator 120 of FIG. .. The oscillation circuit 11 shown in FIG. 18 is a CR oscillation circuit that utilizes the hysteresis characteristic of the Schmitt trigger, but is not necessarily limited to such a CR oscillation circuit, and the electrostatic capacitance component of the actuator (including the diaphragm) Any oscillator circuit may be used as long as it is an oscillator circuit using the (capacitor C). The oscillator circuit 11 may be configured to use, for example, an LC oscillator circuit. Further, in the present embodiment, an example in which a Schmitt trigger inverter is used has been described, but, for example, a CR oscillation circuit using three stages of inverters may be configured.

In the inkjet head 100 shown in FIG. 3, as described above, the diaphragm 121 and the segment electrode 122 separated by a very small space (void) form the electrostatic actuator 120 that forms the counter electrode. This electrostatic actuator 120 can be considered as a parallel plate capacitor as shown in FIG. The capacitance of this capacitor is C, the surface area of each of the diaphragm 121 and the segment electrode 122 is S, the distance (gap length) between the two electrodes 121 and 122 is g, and the dielectric of the space (gap) sandwiched between both electrodes is the rate epsilon ₍₀ vacuum permittivity epsilon, when the relative dielectric constant of the space and _{ε r, ε = ε 0 ·} ε r) when to the capacitance C of the capacitor shown in FIG. 17 (electrostatic actuator 120) (X) is expressed by the following equation.

In addition, as shown in FIG. 17, x in the equation (4) indicates the amount of displacement of the diaphragm 121 from the reference position caused by the residual vibration of the diaphragm 121.

As can be seen from the equation (4), the capacitance C(x) increases as the gap length g (gap length g-displacement amount x) decreases, and conversely, the gap length g (gap length g-displacement amount). As x) increases, the capacitance C(x) decreases. Thus, the electrostatic capacitance C(x) is inversely proportional to (gap length g-displacement amount x) (when x is 0, the gap length g). In the electrostatic actuator 120 shown in FIG. 3, since the void is filled with air, the relative permittivity ε _r =1.

Further, generally, as the resolution of the droplet discharge device (the inkjet printer 1 in the present embodiment) increases, the discharged ink droplets (ink dots) are miniaturized, so that the electrostatic actuator 120 has a high density. , Be miniaturized. As a result, the surface area S of the vibration plate 121 of the inkjet head 100 is reduced, and the small electrostatic actuator 120 is configured. Furthermore, since the gap length g of the electrostatic actuator 120, which changes due to the residual vibration due to the ink droplet ejection, is about 10% of the initial gap g ₀ , the electrostatic capacitance of the electrostatic actuator 120 is as shown in equation (4). The change amount of is a very small value.

In order to detect the amount of change in the electrostatic capacitance of the electrostatic actuator 120 (depending on the vibration pattern of the residual vibration), the following method is used, that is, as shown in FIG. 18 based on the electrostatic capacitance of the electrostatic actuator 120. A method for analyzing the frequency (cycle) of the residual vibration based on the oscillated signal is used. The oscillation circuit 11 shown in FIG. 18 includes a capacitor (C) including an electrostatic actuator 120, a Schmitt trigger inverter 111, and a resistance element (R) 112.

When the output signal of the Schmitt trigger inverter 111 is High level, the capacitor C is charged via the resistance element 112. When the charging voltage of the capacitor C (potential difference between the diaphragm 121 and the segment electrode 122) reaches the input threshold voltage V _T + of the Schmitt trigger inverter 111, the output signal of the Schmitt trigger inverter 111 is inverted to Low level. Then, when the output signal of the Schmitt trigger inverter 111 becomes Low level, the electric charge stored in the capacitor C is discharged via the resistance element 112. When the voltage of the capacitor C reaches the input threshold voltage V _T − of the Schmitt trigger inverter 111 due to this discharge, the output signal of the Schmitt trigger inverter 111 is inverted to High level again. After that, this oscillation operation is repeated.

Here, in order to detect the time change of the electrostatic capacitance of the capacitor C in each of the above-mentioned phenomena (air bubble mixing, drying, paper dust adhesion, and normal ejection), the oscillation frequency by the oscillation circuit 11 is the residual vibration. It is necessary to set the oscillation frequency at which the highest frequency can be detected when bubbles are mixed (see FIG. 10). Therefore, the oscillation frequency of the oscillation circuit 11 must be, for example, several times to several tens of times or more the frequency of the residual vibration to be detected, that is, a frequency higher by about one digit or more than the frequency when bubbles are mixed. In this case, preferably, the frequency of the residual vibration when the bubbles are mixed is higher than that in the case of normal ejection, so that the residual vibration frequency when the bubbles are mixed may be set to a detectable oscillation frequency. Otherwise, the frequency of the residual vibration cannot be detected accurately with respect to the phenomenon of abnormal discharge. Therefore, in this embodiment, the CR time constant of the oscillation circuit 11 is set according to the oscillation frequency. By thus setting the oscillation frequency of the oscillation circuit 11 high, a more accurate residual vibration waveform can be detected based on this minute change in the oscillation frequency.

It should be noted that for each cycle (pulse) of the oscillation frequency of the oscillation signal output from the oscillation circuit 11, the pulse is counted using a count pulse for measurement (counter), and the capacitance of the capacitor C in the initial gap g ₀ is counted. By subtracting the count amount of the pulse of the oscillation frequency in the case of oscillating from the measured count amount, digital information for each oscillation frequency of the residual vibration waveform is obtained. By performing digital/analog (D/A) conversion based on these digital information, a rough residual vibration waveform can be generated. Although such a method may be used, a count pulse (counter) for measurement needs to have a high frequency (high resolution) capable of measuring a minute change in the oscillation frequency. In order to increase the cost of such a count pulse (counter), the ejection abnormality detecting means 10 uses the F/V conversion circuit 12 shown in FIG.

FIG. 19 is a circuit diagram of the F/V conversion circuit 12 of the ejection abnormality detecting means 10 shown in FIG. As shown in FIG. 19, the F/V conversion circuit 12 includes three switches SW1, SW2, and SW3, two capacitors C1 and C2, a resistance element R1, and a constant current source 13 that outputs a constant current Is. , And a buffer 14. The operation of the F/V conversion circuit 12 will be described with reference to the timing chart of FIG. 20 and the graph of FIG.

First, a method of generating the charge signal, the hold signal and the clear signal shown in the timing chart of FIG. 20 will be described. The charging signal is generated by setting the fixed time tr from the rising edge of the oscillation pulse of the oscillation circuit 11 and keeping it at the High level for the fixed time tr. The hold signal is generated such that it rises in synchronization with the rising edge of the charging signal, is held at the high level for a predetermined fixed time, and falls to the low level. The clear signal is generated such that it rises in synchronization with the falling edge of the hold signal, is held at the high level for a predetermined fixed time, and falls to the low level. As will be described later, since the transfer of electric charge from the condenser C1 to the condenser C2 and the discharge of the condenser C1 are performed instantaneously, the pulses of the hold signal and the clear signal are delayed until the next rising edge of the output signal of the oscillation circuit 11. Need only include one pulse each, and is not limited to the rising edge and the falling edge as described above.

A method for setting the fixed times tr and t1 will be described with reference to FIG. 21 in order to obtain a clean residual vibration waveform (voltage waveform). The fixed time tr is adjusted from the cycle of the oscillation pulse oscillated by the electrostatic capacitance C when the electrostatic actuator 120 has the initial gap length g ₀ , and the charging potential at the charging time t1 is about ½ of the charging range of C1. Is set. Further, the inclination of the charging potential is set so as not to exceed the charging range of the capacitor C1 between the charging time t2 at the position where the gap length g is maximum (Max) and the charging time t3 at the position where the gap length g is minimum (Min). That is, since the slope of the charging potential is determined by dV/dt=Is/C1, the output constant current Is of the constant current source 13 may be set to an appropriate value. By setting the output constant current Is of the constant current source 13 as high as possible within the range, it is possible to detect a minute change in the electrostatic capacitance of the capacitor constituted by the electrostatic actuator 120 with high sensitivity, and it is possible to detect static electricity. It becomes possible to detect a minute change of the diaphragm 121 of the electric actuator 120.

Next, the configuration of the waveform shaping circuit 15 shown in FIG. 16 will be described with reference to FIG. 22 is a circuit diagram showing a circuit configuration of the waveform shaping circuit 15 of FIG. The waveform shaping circuit 15 outputs the residual vibration waveform to the determination means 20 as a rectangular wave. As shown in FIG. 22, the waveform shaping circuit 15 includes two capacitors C3 (DC component removing means), C4, two resistance elements R2 and R3, two DC voltage sources Vref1 and Vref2, and an amplifier (opamp). ) 151 and a comparator 152. In the waveform shaping process of the residual vibration waveform, the detected peak value may be output as it is, and the amplitude of the residual vibration waveform may be measured.

The output of the buffer 14 of the F/V conversion circuit 12 contains a capacitance component of a DC component (direct current component) based on the initial gap g ₀ of the electrostatic actuator 120. Since this DC component varies among the inkjet heads 100, the capacitor C3 removes the DC component of this capacitance. Then, the capacitor C3 removes the DC component in the output signal of the buffer 14 and outputs only the AC component of the residual vibration to the inverting input terminal of the operational amplifier 151.

The operational amplifier 151 constitutes a low-pass filter for inverting and amplifying the output signal of the buffer 14 of the F/V conversion circuit 12 from which the DC component is removed, and for removing the high frequency band of the output signal. The operational amplifier 151 is assumed to be a single power supply circuit. The operational amplifier 151 constitutes an inverting amplifier composed of two resistance elements R2 and R3, and the input residual vibration (AC component) is amplified by -R3/R2 times.

Further, due to the single power supply operation of the operational amplifier 151, the amplified residual vibration waveform of the diaphragm 121, which oscillates around the potential set by the DC voltage source Vref1 connected to the non-inverting input terminal, is output. .. Here, the DC voltage source Vref1 is set to about ½ of the voltage range in which the operational amplifier 151 can operate with a single power source. Further, the operational amplifier 151 constitutes a low-pass filter having a cutoff frequency of 1/(2π×C4×R3) by the two capacitors C3 and C4. Then, the residual vibration waveform of the diaphragm 121 amplified after the DC component is removed is, as shown in the timing chart of FIG. 20, the potential of another DC voltage source Vref2 in the comparator 152 of the next stage. And the result of the comparison is output from the waveform shaping circuit 15 as a rectangular wave. The DC voltage source Vref2 may share the other DC voltage source Vref1.

Next, operations of the F/V conversion circuit 12 and the waveform shaping circuit 15 of FIG. 19 will be described with reference to the timing chart shown in FIG. The F/V conversion circuit 12 shown in FIG. 19 operates based on the charge signal, the clear signal, and the hold signal generated as described above. In the timing chart of FIG. 20, when the drive signal of the electrostatic actuator 120 is input to the inkjet head 100 via the head driver 33, the diaphragm 121 of the electrostatic actuator 120 is segmented as shown in FIG. 6B. It is attracted to the electrode 122 side and, in synchronization with the falling edge of this drive signal, it contracts rapidly upward in FIG. 6 (see FIG. 6C).

In synchronization with the falling edge of this drive signal, the drive/detection switching signal that switches between the drive circuit 18 and the ejection abnormality detection means 10 becomes High level. The drive/detection switching signal is held at the high level during the drive suspension period of the corresponding inkjet head 100, and becomes the low level before the next drive signal is input. While the drive/detection switching signal is at the high level, the oscillation circuit 11 in FIG. 18 oscillates while changing the oscillation frequency according to the residual vibration of the diaphragm 121 of the electrostatic actuator 120.

As described above, from the falling edge of the drive signal, that is, the rising edge of the output signal of the oscillation circuit 11, for a fixed time tr set in advance so that the waveform of the residual vibration does not exceed the chargeable range of the capacitor C1. The charge signal is held at the high level until the time elapses. Note that the switch SW1 is off while the charge signal is at the high level.

When the fixed time tr has elapsed and the charge signal becomes low level, the switch SW1 is turned on in synchronization with the falling edge of the charge signal (see FIG. 19). Then, the constant current source 13 and the capacitor C1 are connected, and the capacitor C1 is charged with the slope Is/C1 as described above. The capacitor C1 is charged during the period when the charge signal is at the Low level, that is, until it becomes the High level in synchronization with the rising edge of the next pulse of the output signal of the oscillation circuit 11.

When the charging signal becomes High level, the switch SW1 is turned off (open), and the constant current source 13 and the capacitor C1 are disconnected. At this time, the capacitor C1 stores the potential (that is, ideally Is×t1/C1 (V)) charged during the period t1 when the charge signal is at the Low level. In this state, when the hold signal becomes High level, the switch SW2 is turned on (see FIG. 19), and the capacitors C1 and C2 are connected via the resistance element R1. After the switch SW2 is connected, the two capacitors C1 and C2 are charged and discharged with each other by the charging potential difference, and the charges are transferred from the capacitor C1 to the capacitor C2 so that the potential differences between the two capacitors C1 and C2 are substantially equal.

Here, the capacitance of the capacitor C2 is set to about 1/10 or less of the capacitance of the capacitor C1. Therefore, the amount of charge that is moved (used) by charge and discharge caused by the potential difference between the two capacitors C1 and C2 is 1/10 or less of the charge charged in the capacitor C1. Therefore, even after the charge is transferred from the capacitor C1 to the capacitor C2, the potential difference of the capacitor C1 does not change much (it does not decrease so much). In the F/V conversion circuit 12 of FIG. 19, when the capacitor C2 is charged, in order to prevent the charging potential from suddenly jumping up due to the inductance of the wiring of the F/V conversion circuit 12, the resistance element R1 and the capacitor C2 constitutes a first-order low-pass filter.

After the charge potential substantially equal to the charge potential of the capacitor C1 is held in the capacitor C2, the hold signal becomes Low level, and the capacitor C1 is separated from the capacitor C2. Further, when the clear signal becomes High level and the switch SW3 is turned on, the capacitor C1 is connected to the ground GND, and the discharging operation is performed so that the electric charge charged in the capacitor C1 becomes zero. After discharging the capacitor C1, the clear signal becomes Low level, and the switch SW3 is turned off, so that the upper electrode in FIG. 19 of the capacitor C1 is disconnected from the ground GND, that is, until the next charging signal is input, that is, charging Waiting until the signal goes to the low level.

The potential held in the capacitor C2 is updated at each rising timing of the charging signal, that is, every time the charging of the capacitor C2 is completed, and the residual vibration waveform of the diaphragm 121 via the buffer 14 shown in FIG. It is output to the shaping circuit 15. Therefore, the electrostatic capacitance of the electrostatic actuator 120 (in this case, the variation width of the electrostatic capacitance due to residual vibration must also be considered) and the resistance value of the resistance element 112 are set so that the oscillation frequency of the oscillation circuit 11 becomes high. By doing so, each step (step) of the potential of the capacitor C2 (output of the buffer 14) shown in the timing chart of FIG. 20 becomes more detailed, so that the temporal change of the capacitance due to the residual vibration of the diaphragm 121 is further improved. It is possible to detect in detail.

Similarly, the charge signal is repeated from the Low level to the High level to the Low level, and the potential held in the capacitor C2 is output to the waveform shaping circuit 15 via the buffer 14 at the predetermined timing. In the waveform shaping circuit 15, the DC component of the voltage signal (potential of the capacitor C2 in the timing chart of FIG. 20) input from the buffer 14 is removed by the capacitor C3, and is input to the inverting input terminal of the operational amplifier 151 via the resistance element R2. Is entered. The input alternating current (AC) component of the residual vibration is inverted and amplified by the operational amplifier 151 and output to one input terminal of the comparator 152. The comparator 152 compares the potential (reference voltage) preset by the DC voltage source Vref2 with the potential of the residual vibration waveform (AC component) and outputs a rectangular wave (of the comparison circuit in the timing chart of FIG. 20). output).

Next, the switching timing between the ink droplet ejection operation (driving) and the ejection abnormality detection operation (driving suspension) of the inkjet head 100 will be described. FIG. 23 is a block diagram showing an outline of the switching means 23 between the drive circuit 18 and the ejection abnormality detecting means 10. In FIG. 23, the drive circuit 18 in the head driver 33 shown in FIG. 16 will be described as a drive circuit of the inkjet head 100. As shown in the timing chart of FIG. 20, the ejection abnormality detection process is executed between the drive signals of the inkjet head 100, that is, in the drive suspension period.

In FIG. 23, in order to drive the electrostatic actuator 120, the switching means 23 is initially connected to the drive circuit 18 side. As described above, when the drive signal (voltage signal) is input from the drive circuit 18 to the diaphragm 121, the electrostatic actuator 120 is driven, the diaphragm 121 is attracted to the segment electrode 122 side, and the applied voltage is 0. Then, it is abruptly displaced in the direction away from the segment electrode 122 to start vibration (residual vibration). At this time, ink droplets are ejected from the nozzles 110 of the inkjet head 100.

When the pulse of the drive signal falls, the drive/detection switching signal (see the timing chart of FIG. 20) is input to the switching means 23 in synchronization with the falling edge, and the switching means 23 detects the ejection abnormality from the drive circuit 18. It is switched to the means (detection circuit) 10 side, and the electrostatic actuator 120 (used as a capacitor of the oscillation circuit 11) is connected to the ejection abnormality detection means 10.

Then, the ejection abnormality detection means 10 executes the above-described ejection abnormality (dot omission) detection processing, and outputs residual vibration waveform data (rectangular wave data) of the diaphragm 121 output from the comparator 152 of the waveform shaping circuit 15. ) Is quantified by the measuring means 17 into the period and amplitude of the residual vibration waveform. In the present embodiment, the measuring means 17 measures a specific vibration cycle from the residual vibration waveform data and outputs the measurement result (numerical value) to the judging means 20.

Specifically, the measuring unit 17 measures the time (the cycle of residual vibration) from the first rising edge to the next rising edge of the waveform (rectangular wave) of the output signal of the comparator 152, so that a counter (not shown) is provided. The pulse of the reference signal (predetermined frequency) is counted by using, and the cycle of the residual vibration (specific vibration cycle) is measured from the count value. The measuring means 17 may measure the time from the first rising edge to the next falling edge and output the time twice as long as the measured time to the determining means 20 as the cycle of the residual vibration. Hereinafter, the cycle of the residual vibration obtained in this way is referred to as Tw.

The determination unit 20 determines the presence/absence of ejection abnormality of the nozzle, the cause of ejection abnormality, the amount of comparison deviation, and the like based on a specific vibration cycle (measurement result) of the residual vibration waveform measured by the measurement unit 17, and the like. The determination result is output to the control unit 6. The control unit 6 saves this determination result in a predetermined storage area of the EEPROM (storage means) 62. Then, at the timing when the next drive signal from the drive circuit 18 is input, the drive/detection switching signal is input again to the switching means 23 to connect the drive circuit 18 and the electrostatic actuator 120. Since the drive circuit 18 maintains the ground (GND) level once the drive voltage is applied, the switching unit 23 performs the above-described switching (see the timing chart of FIG. 20). Accordingly, the residual vibration waveform of the diaphragm 121 of the electrostatic actuator 120 can be accurately detected without being affected by the disturbance from the drive circuit 18.

It should be noted that the residual vibration waveform data is not limited to the rectangular wave formed by the comparator 152. For example, the residual vibration amplitude data output from the operational amplifier 151 is digitized at any time by the measurement means 17 that performs A/D conversion without performing comparison processing by the comparator 152, and based on the digitized data, The determination unit 20 may be configured to determine whether or not there is an ejection abnormality and store the determination result in the storage unit 62.

Further, since the meniscus of the nozzle 110 (the surface where the ink inside the nozzle 110 is in contact with the atmosphere) vibrates in synchronization with the residual vibration of the vibration plate 121, the inkjet head 100 causes the residual vibration of the meniscus after the ink droplet ejection operation. After waiting for the sound resistance to decay at a time substantially determined by the acoustic resistance r (waiting for a predetermined time), the next ejection operation is performed. In this embodiment, the standby time is effectively used to detect the residual vibration of the diaphragm 121, so that it is possible to perform the ejection abnormality detection that does not affect the driving of the inkjet head 100. That is, the ejection abnormality detection process of the nozzles 110 of the inkjet head 100 can be executed without lowering the throughput of the inkjet printer 1 (droplet ejection device).

As described above, when air bubbles are mixed in the cavity 141 of the inkjet head 100, the frequency becomes higher than the residual vibration waveform of the vibration plate 121 at the time of normal ejection, so the cycle thereof is conversely at the time of normal ejection. It becomes shorter than the cycle of residual vibration. Further, when the ink near the nozzle 110 is thickened and fixed due to drying, the residual vibration is overdamped, and the frequency is considerably lower than the residual vibration waveform at the time of normal ejection. It is much longer than the cycle of residual vibration. Further, when paper dust adheres to the vicinity of the outlet of the nozzle 110, the frequency of residual vibration is lower than the frequency of residual vibration during normal ejection, but higher than the frequency of residual vibration during ink drying. Therefore, the cycle is longer than the cycle of residual vibration during normal ejection and shorter than the cycle of residual vibration during ink drying.

Therefore, a predetermined range Tr is provided as the cycle of the residual vibration at the time of normal ejection, the cycle of the residual vibration when the paper dust adheres to the outlet of the nozzle 110, and the case where the ink is dried near the outlet of the nozzle 110. By setting a predetermined threshold value (predetermined threshold value) T1 in order to distinguish it from the cycle of the residual vibration, the cause of such ejection abnormality of the inkjet head 100 can be determined. The determination means 20 determines whether or not the cycle Tw of the residual vibration waveform detected by the above-described ejection abnormality detection process is within a predetermined range, and is longer than a predetermined threshold value. The cause of the discharge abnormality is determined by.

Next, the operation of the droplet discharge device of the present embodiment will be described based on the configuration of the inkjet printer 1 described above. First, the ejection abnormality detection process (including the drive/detection switching process) for the nozzle 110 of one ink jet head 100 will be described. FIG. 24 is a flowchart showing the ejection abnormality detection/determination processing. When print data to be printed (which may be ejection data in the flushing operation) is input from the host computer 8 to the control unit 6 via the interface (IF) 9, the ejection abnormality detection process is executed at a predetermined timing. Note that, for convenience of description, the flowchart shown in FIG. 24 shows an ejection abnormality detection process corresponding to the ejection operation of one inkjet head 100, that is, one nozzle 110.

First, a drive signal corresponding to print data (ejection data) is input from the drive circuit 18 of the head driver 33, whereby the electrostatic actuator 120 of the electrostatic actuator 120 is driven based on the timing of the drive signal as shown in the timing chart of FIG. A drive signal (voltage signal) is applied between both electrodes (step S101). Then, the control unit 6 determines, based on the drive/detection switching signal, whether the ejected inkjet head 100 is in the drive suspension period (step S102). Here, the drive/detection switching signal becomes High level in synchronization with the falling edge of the driving signal (see FIG. 20), and is input from the control unit 6 to the switching unit 23.

When the drive/detection switching signal is input to the switching unit 23, the switching unit 23 disconnects the electrostatic actuator 120, that is, the capacitor forming the oscillation circuit 11 from the driving circuit 18, and the ejection abnormality detection unit 10 (detection). (Circuit) side, that is, the oscillation circuit 11 of the residual vibration detecting means 16 (step S103). Then, the residual vibration detecting process described later is executed (step S104), and the measuring means 17 measures a predetermined numerical value from the residual vibration waveform data detected in the residual vibration detecting process (step S105). Here, as described above, the measuring means 17 measures the period of the residual vibration from the residual vibration waveform data.

Next, the determination unit 20 executes an ejection abnormality determination process, which will be described later, based on the measurement result of the measurement unit (step S106), and stores the determination result in a predetermined storage area of the EEPROM (storage unit) 62 of the control unit 6. save. Then, in step S108, it is determined whether or not the inkjet head 100 is in the drive period. That is, it is determined whether or not the next drive signal is input after the end of the drive suspension period, and the process waits in step S108 until the next drive signal is input.

When the drive/detection switching signal becomes Low level in synchronization with the rising edge of the driving signal at the timing when the pulse of the next driving signal is input (“yes” in step S108), the switching unit 23 causes the electrostatic actuator 120 to operate. The connection with is switched from the discharge abnormality detection means (detection circuit) 10 to the drive circuit 18 (step S109), and this discharge abnormality detection process is ended.

The flowchart shown in FIG. 24 shows the case where the measuring unit 17 measures the cycle from the residual vibration waveform detected by the residual vibration detecting process (residual vibration detecting unit 16), but the present invention is not limited to such a case. For example, the measuring means 17 may measure the phase difference or the amplitude of the residual vibration waveform from the residual vibration waveform data detected in the residual vibration detection process.

Next, the residual vibration detection process (subroutine) in step S104 of the flowchart shown in FIG. 24 will be described. FIG. 25 is a flowchart showing the residual vibration detection processing. As described above, when the switching means 23 connects the electrostatic actuator 120 and the oscillation circuit 11 (step S103 in FIG. 24), the oscillation circuit 11 constitutes a CR oscillation circuit, and the electrostatic capacitance of the electrostatic actuator 120 is increased. (The residual vibration of the diaphragm 121 of the electrostatic actuator 120) is oscillated (step S201).

As shown in the above timing chart and the like, the F/V conversion circuit 12 generates a charge signal, a hold signal, and a clear signal based on the output signal (pulse signal) of the oscillation circuit 11, and based on these signals. The F/V conversion circuit 12 performs F/V conversion processing for converting the frequency of the output signal of the oscillation circuit 11 into a voltage (step S202), and the F/V conversion circuit 12 outputs residual vibration waveform data of the diaphragm 121. To be done. In the residual vibration waveform data output from the F/V conversion circuit 12, the DC component (DC component) is removed by the capacitor C3 of the waveform shaping circuit 15 (step S203), and the DC component is removed by the operational amplifier 151. The vibration waveform (AC component) is amplified (step S204).

The residual vibration waveform data after amplification is waveform-shaped by a predetermined process and pulsed (step S205). That is, in the present embodiment, the comparator 152 compares the voltage value (predetermined voltage value) set by the DC voltage source Vref2 with the output voltage of the operational amplifier 151. The comparator 152 outputs a binarized waveform (rectangular wave) based on the comparison result. The output signal of the comparator 152 is the output signal of the residual vibration detecting means 16 and is output to the measuring means 17 for performing the discharge abnormality determination processing, and the residual vibration detecting processing ends.

Next, the discharge abnormality determination process (subroutine) in step S106 of the flowchart shown in FIG. 24 will be described. FIG. 26 is a flowchart showing the ejection abnormality determination processing executed by the controller 6 and the determination means 20. Based on the measurement data (measurement result) such as the cycle measured by the above-described measuring unit 17, the determining unit 20 determines whether or not the ink droplet is normally discharged from the corresponding inkjet head 100, and does not discharge normally. In the case, that is, in the case of abnormal ejection, it is determined what the cause is.

First, the control unit 6 outputs the predetermined range Tr of the cycle of residual vibration and the predetermined threshold T1 of the cycle of residual vibration stored in the EEPROM 62 to the determination means 20. The predetermined range Tr of the cycle of the residual vibration has a permissible range in which it can be determined to be normal with respect to the residual vibration cycle during normal ejection. These data are stored in a memory (not shown) of the judging means 20, and the following processing is executed.

The measurement result measured by the measuring means 17 in step S105 of FIG. 24 is input to the determining means 20 (step S301). Here, in the present embodiment, the measurement result is the cycle Tw of the residual vibration of the diaphragm 121.

In step S202, the determination unit 20 determines whether or not the residual vibration period Tw exists, that is, whether or not the residual vibration waveform data has not been obtained by the ejection abnormality detection unit 10. When it is determined that the residual vibration period Tw does not exist, the determination unit 20 determines that the nozzle 110 of the inkjet head 100 is a non-ejection nozzle that has not ejected an ink droplet in the ejection abnormality detection process ( Step S306). If it is determined that the residual vibration waveform data exists, then in step S303, the determination unit 20 determines whether or not the cycle Tw is within a predetermined range Tr recognized as a cycle during normal ejection. To judge.

When it is determined that the cycle Tw of the residual vibration is within the predetermined range Tr, it means that the ink droplets are normally ejected from the corresponding inkjet head 100, and the determining unit 20 determines that the inkjet head 100 The nozzle 110 determines that the ink droplet is normally ejected (normal ejection) (step S307). When it is determined that the cycle Tw of residual vibration is not within the predetermined range Tr, subsequently, in step S304, the determination unit 20 determines whether the cycle Tw of residual vibration is shorter than the predetermined range Tr. Determine whether.

When it is determined that the cycle Tw of the residual vibration is shorter than the predetermined range Tr, it means that the frequency of the residual vibration is high, and as described above, air bubbles are mixed in the cavity 141 of the inkjet head 100. It is considered that there is air bubbles, and the determination unit 20 determines that air bubbles are contained in the cavity 141 of the inkjet head 100 (air bubbles are contained) (step S308).

Further, when it is determined that the cycle Tw of residual vibration is longer than the predetermined range Tr, the determination means 20 subsequently determines whether the cycle Tw of residual vibration is longer than the predetermined threshold value T1. The determination is made (step S305). When it is determined that the cycle Tw of the residual vibration is longer than the predetermined threshold value T1, it is considered that the residual vibration is overdamped, and the determination unit 20 determines that the ink near the nozzle 110 of the inkjet head 100 is It is determined that the viscosity has increased due to drying (drying) (step S309).

Then, in step S305, when it is determined that the cycle Tw of the residual vibration is shorter than the predetermined threshold value T1, the cycle Tw of the residual vibration is a value in the range satisfying Tr<Tw<T1, As described above, it is considered that the paper powder adheres to the vicinity of the outlet of the nozzle 110 having a frequency higher than that of the drying, and the determination unit 20 has the paper powder adhered to the vicinity of the outlet of the nozzle 110 of the inkjet head 100. It is determined that (paper dust is attached) (step S310).

In this way, when the determination unit 20 determines the cause of the normal ejection or the ejection abnormality of the target inkjet head 100 (steps S306 to S310), the determination result is output to the control unit 6, and the ejection is performed. The abnormality determination process ends.

Next, assuming a plurality of inkjet heads (droplet ejection heads) 100, that is, an inkjet printer 1 having a plurality of nozzles 110, the ejection selection unit (nozzle selector) 182 in the inkjet printer 1 and each inkjet head 100. The timing of the discharge abnormality detection/judgment will be described.

In addition, in order to make the description easy to understand, one head unit 35 of the plurality of head units 35 included in the printing unit 3 will be described below, and the head unit 35 includes five inkjet heads 100a to 100e. However, the number of head units 35 included in the printing unit 3 and the number of inkjet heads 100 (nozzles 110) included in each head unit 35 are different. May be.

27 to 30 are block diagrams showing some examples of ejection abnormality detection/determination timing in the inkjet printer 1 including the ejection selection unit 182. Hereinafter, the configuration example of each drawing will be sequentially described.

FIG. 27 shows an example of the timing of the ejection abnormality detection of a plurality of (five) inkjet heads 100a to 100e (in the case of one ejection abnormality detection means 10). As shown in FIG. 27, the inkjet printer 1 having a plurality of inkjet heads 100a to 100e can select a drive waveform generation unit 181 that generates a drive waveform and which nozzle 110 ejects an ink droplet. It is equipped with a discharge selection unit 182 capable of performing discharge, and a plurality of inkjet heads 100a to 100e selected by the discharge selection unit 182 and driven by the drive waveform generation unit 181. The configuration of FIG. 27 is the same as that shown in FIG. 2, FIG. 16 and FIG. 23 except for the above, and therefore its description is omitted.

In the present embodiment, the drive waveform generation unit 181 and the ejection selection unit 182 will be described as being included in the drive circuit 18 of the head driver 33 (in FIG. 27, shown as two blocks via the switching unit 23). However, in general, both are configured in the head driver 33), and the configuration is not limited to this. For example, the drive waveform generation unit 181 may be configured independently of the head driver 33.

As shown in FIG. 27, the ejection selection unit 182 includes a shift register 182a, a latch circuit 182b, and a driver 182c. The shift register 182a is sequentially input with print data (ejection data) output from the host computer 8 shown in FIG. 2 and subjected to a predetermined process in the controller 6, and a clock signal (CLK). The print data is sequentially shifted from the first stage of the shift register 182a to the subsequent stage in response to the input pulse of the clock signal (CLK) (every time the clock signal is input), and is input to the inkjet heads 100a to 100e. The print data is output to the latch circuit 182b. In the ejection abnormality detection process described later, the ejection data at the time of flushing (preliminary ejection) is input instead of the print data. The ejection data means the print data for all the inkjet heads 100a to 100e. .. During flushing, hardware processing may be performed so that all outputs of the latch circuit 182b are set to values that cause ejection.

The latch circuit 182b stores the print data corresponding to the number of the nozzles 110 of the head unit 35, that is, the number of the inkjet heads 100 in the shift register 182a, and then outputs each output signal of the shift register 182a according to the input latch signal. To latch. Here, when the CLEAR signal is input, the latched state is released, the latched output signal of the shift register 182a becomes 0 (latch output is stopped), and the printing operation is stopped. If the CLEAR signal is not input, the latched print data of the shift register 182a is output to the driver 182c. After the print data output from the shift register 182a is latched by the latch circuit 182b, the next print data is input to the shift register 182a, and the latch signal of the latch circuit 182b is sequentially updated at the print timing.

The driver 182c connects the drive waveform generation unit 181 and the electrostatic actuator 120 of each inkjet head 100, and each electrostatic actuator 120 (inkjet) specified (specified) by the latch signal output from the latch circuit 182b. An output signal (driving signal) of the driving waveform generation unit 181 is input to any or all of the electrostatic actuators 120 of the heads 100a to 100e, so that the driving signal (voltage signal) is applied to both electrodes of the electrostatic actuator 120. Applied between.

In the inkjet printer 1 shown in FIG. 27, one drive waveform generation unit 181 that drives a plurality of inkjet heads 100a to 100e, and an ejection abnormality (ink droplet) to one of the inkjet heads 100a to 100e. Discharge abnormality detection means 10 for detecting non-discharge, storage means 62 for storing (storing) the judgment result of the discharge abnormality obtained by this discharge abnormality detection means 10, drive waveform generation means 181, and discharge abnormality. It is provided with one switching means 23 for switching the detection means 10. Therefore, the inkjet printer 1 drives one or more of the inkjet heads 100a to 100e selected by the driver 182c based on the drive signal input from the drive waveform generation unit 181, and outputs a drive/detection switching signal. Is input to the switching unit 23 after the ejection driving operation, so that the switching unit 23 switches the connection between the drive waveform generating unit 181 and the ejection abnormality detecting unit 10 to the electrostatic actuator 120 of the inkjet head 100, and then the diaphragm 121. On the basis of the residual vibration waveform of (1), the ejection abnormality detection means 10 detects the ejection abnormality (ink droplet non-ejection) in the nozzle 110 of the inkjet head 100, and in the case of the ejection abnormality, the cause thereof is determined.

Then, when this inkjet printer 1 detects and determines an ejection abnormality with respect to the nozzle 110 of one inkjet head 100, the inkjet head 100 specified next based on the drive signal input from the drive waveform generation unit 181 next. The ejection abnormality of the nozzle 110 is detected and determined, and in the same manner, the ejection abnormality of the nozzle 110 of the inkjet head 100 driven by the output signal of the drive waveform generation unit 181 is sequentially detected and determined. Then, as described above, when the residual vibration detecting means 16 detects the residual vibration waveform of the diaphragm 121, the measuring means 17 measures the cycle of the residual vibration waveform based on the waveform data, and the determining means 20 measures. Based on the measurement result of the means 17, whether the discharge is normal or abnormal, and if the discharge is abnormal (head abnormality), the cause of the abnormal discharge is determined and the determination result is output to the storage means 62.

As described above, the inkjet printer 1 shown in FIG. 27 is configured to sequentially detect and determine the ejection abnormality of each nozzle 110 of the plurality of inkjet heads 100a to 100e during the ink droplet ejection driving operation. It suffices to provide only one unit 10 and one switching unit 23, and it is possible to scale down the circuit configuration of the inkjet printer 1 that can detect and determine abnormal discharge, and prevent an increase in manufacturing cost.

FIG. 28 is an example of the timing of the ejection abnormality detection of the plurality of inkjet heads 100 (when the number of the ejection abnormality detection units 10 is the same as the number of the inkjet heads 100 ). The inkjet printer 1 shown in FIG. 28 has one ejection selection unit 182, five ejection abnormality detection units 10a to 10e, five switching units 23a to 23e, and one common to the five inkjet heads 100a to 100e. The drive waveform generation means 181 and one storage means 62 are provided. Since each component has already been described in the description of FIG. 27, the description thereof will be omitted and the connection thereof will be described.

As in the case shown in FIG. 27, the ejection selection unit 182 latches the print data corresponding to each of the inkjet heads 100a to 100e based on the print data (ejection data) input from the host computer 8 and the clock signal CLK. The electrostatic actuator 120 of the inkjet heads 100a to 100e corresponding to the print data is driven according to the drive signal (voltage signal) latched by the drive waveform generation unit 181 and input to the driver 182c. The drive/detection switching signal is input to the switching means 23a to 23e corresponding to all the inkjet heads 100a to 100e, and the switching means 23a to 23e drive/detect regardless of the presence or absence of the corresponding print data (ejection data). After the drive signal is input to the electrostatic actuator 120 of the inkjet head 100 based on the detection switching signal, the connection with the inkjet head 100 is switched from the drive waveform generation unit 181 to the ejection abnormality detection units 10a to 10e.

After the ejection abnormality of each of the inkjet heads 100a to 100e is detected and determined by all the ejection abnormality detecting means 10a to 10e, the determination results of all the inkjet heads 100a to 100e obtained by the detection processing are stored in the storage means 62. The storage means 62 stores the presence/absence of ejection abnormality of each of the inkjet heads 100a to 100e and the cause of the ejection abnormality in a predetermined storage area.

As described above, in the inkjet printer 1 shown in FIG. 28, the plurality of ejection abnormality detection units 10a to 10e are provided corresponding to the nozzles 110 of the plurality of inkjet heads 100a to 100e, and the plurality of switching units 23a corresponding thereto are provided. 23 to 23e, the switching operation is performed to detect the discharge abnormality and determine the cause thereof. Therefore, it is possible to detect the discharge abnormality and determine the cause thereof for all the nozzles 110 at once.

FIG. 29 shows an example of ejection abnormality detection timings of a plurality of inkjet heads 100 (when the number of ejection abnormality detection means 10 is the same as the number of inkjet heads 100 and the ejection abnormality is detected when there is print data). is there. The inkjet printer 1 shown in FIG. 29 is obtained by adding (adding) the switching control means 19 to the configuration of the inkjet printer 1 shown in FIG. In the present embodiment, the switching control means 19 is composed of a plurality of AND circuits (logical product circuits) ANDa to ANDe, and the print data input to each of the inkjet heads 100a to 100e and the drive/detection switching signal are input. Then, a high level output signal is output to the corresponding switching means 23a to 23e. The switching control unit 19 is not limited to the AND circuit (logical product circuit), and may be configured to select the switching unit 23 that matches the output of the latch circuit 182b that selects the inkjet head 100 to be driven. ..

Based on the output signals of the corresponding AND circuits ANDa to ANDe of the switching control means 19, the switching means 23a to 23e from the drive waveform generating means 181 to the corresponding ejection abnormality detection means 10a to 10e, respectively. The connection with the electrostatic actuator 120 of 100a to 100e is switched. Specifically, when the output signals of the corresponding AND circuits ANDa to ANDe are at the high level, that is, when the drive/detection switching signal is at the high level, the print data input to the corresponding inkjet heads 100a to 100e is latched. When output from the circuit 182b to the driver 182c, the switching means 23a to 23e corresponding to the AND circuit connect the corresponding inkjet heads 100a to 100e from the drive waveform generation means 181 to the ejection abnormality detection means 10a. Switch to 10e.

The ejection abnormality detection means 10a to 10e corresponding to the inkjet head 100 to which the print data is input detects the presence or absence of the ejection abnormality of each inkjet head 100 and the cause thereof in the case of the ejection abnormality, and then the ejection abnormality detection means 10 Outputs the determination result obtained by the detection process to the storage unit 62. The storage unit 62 stores one or a plurality of determination results thus input (obtained) in a predetermined storage area.

As described above, in the inkjet printer 1 shown in FIG. 29, the plurality of ejection abnormality detecting units 10a to 10e are provided corresponding to the nozzles 110 of the plurality of inkjet heads 100a to 100e, and the inkjet heads 100a to 100e are supported. When the print data to be printed is input from the host computer 8 to the ejection selection unit 182 via the control unit 6, only the switching units 23a to 23e designated by the switching control unit 19 perform a predetermined switching operation, and the inkjet head Since the ejection abnormality detection of 100 and its cause determination are performed, this detection/determination processing is not performed for the inkjet head 100 that is not performing the ejection driving operation. Therefore, the inkjet printer 1 can avoid unnecessary detection and determination processing.

FIG. 30 shows an example of the timing of the discharge abnormality detection of the plurality of inkjet heads 100 (when the number of the discharge abnormality detecting units 10 is the same as the number of the inkjet heads 100 and the discharge abnormality detection is performed by circulating each inkjet head 100). ). The inkjet printer 1 shown in FIG. 30 has one ejection abnormality detection unit 10 in the configuration of the inkjet printer 1 shown in FIG. 29, and scans a drive/detection switching signal (an inkjet head 100 that executes a detection/determination process). Switching selection means 19a is added).

The switching selection unit 19a is connected to the switching control unit 19 shown in FIG. 29, and corresponds to the plurality of inkjet heads 100a to 100e based on the scanning signal (selection signal) input from the control unit 6. A selector that scans (selects and switches) the input of the drive/detection switching signal to the AND circuits ANDa to ANDe. The scanning (selection) order of the switching selection means 19a may be the order of the print data input to the shift register 182a, that is, the ejection order of the plurality of inkjet heads 100, but simply the plurality of inkjet heads 100a to 100a. The order may be 100e.

When the scan order is the order of the print data input to the shift register 182a, when the print data is input to the shift register 182a of the ejection selection unit 182, the print data is latched by the latch circuit 182b and the latch signal is input. Is output to the driver 182c. In synchronization with the input of the print data to the shift register 182a or the input of the latch signal to the latch circuit 182b, a scanning signal for specifying the inkjet head 100 corresponding to the print data is input to the switching selection means 19a, and the corresponding The drive/detection switching signal is output to the AND circuit. The output terminal of the switching selection means 19a outputs Low level when not selected.

The corresponding AND circuit (switching control unit 19) performs a logical product operation of the print data input from the latch circuit 182b and the drive/detection switching signal input from the switching selection unit 19a to output a High level output. The signal is output to the corresponding switching means 23. Then, the switching means 23 to which the high level output signal is input from the switching control means 19 switches the connection of the corresponding inkjet head 100 to the electrostatic actuator 120 from the drive waveform generation means 181 to the ejection abnormality detection means 10.

The ejection abnormality detection unit 10 detects the ejection abnormality of the inkjet head 100 to which the print data is input, determines the cause of the ejection abnormality, and outputs the determination result to the storage unit 62. Then, the storage unit 62 stores the determination result thus input (obtained) in a predetermined storage area.

Further, when the print order is the order of the simple inkjet heads 100a to 100e, when the print data is input to the shift register 182a of the ejection selection unit 182, the print data is latched by the latch circuit 182b and the latch signal is input. Is output to the driver 182c. A scanning (selection) signal for specifying the inkjet head 100 corresponding to the print data is input to the switching selection unit 19a in synchronization with the input of the print data to the shift register 182a or the input of the latch signal to the latch circuit 182b. Then, the drive/detection switching signal is output to the corresponding AND circuit of the switching control means 19.

Here, when the print data for the inkjet head 100 determined by the scanning signal input to the switching selection unit 19a is input to the shift register 182a, the output signal of the corresponding AND circuit (switching control unit 19) is High level. Therefore, the switching unit 23 switches the connection to the corresponding inkjet head 100 from the drive waveform generation unit 181 to the ejection abnormality detection unit 10. However, when the print data is not input to the shift register 182a, the output signal of the AND circuit is Low level, and the corresponding switching unit 23 does not execute the predetermined switching operation. Therefore, the ejection abnormality detection process of the inkjet head 100 is performed based on the logical product of the selection result of the switching selection unit 19a and the result designated by the switching control unit 19.

When the switching operation is performed by the switching unit 23, the ejection abnormality detecting unit 10 detects the ejection abnormality of the inkjet head 100 to which the print data is input, and when there is the ejection abnormality, the same as above. After determining the cause, the determination result is output to the storage unit 62. Then, the storage unit 62 stores the determination result thus input (obtained) in a predetermined storage area.

When there is no print data for the inkjet head 100 specified by the switching selection unit 19a, the corresponding switching unit 23 does not perform the switching operation as described above, and thus the ejection abnormality detection process by the ejection abnormality detection unit 10 is executed. However, such processing may be performed. When the ejection abnormality detection process is executed without performing the switching operation, the determination unit 20 of the ejection abnormality detection unit 10 determines that the nozzle 110 of the corresponding inkjet head 100 is a non-ejection nozzle, as shown in the flowchart of FIG. Is determined (step S306), and the determination result is stored in a predetermined storage area of the storage unit 62.

As described above, in the inkjet printer 1 shown in FIG. 30, unlike the inkjet printer 1 shown in FIG. 28 or 29, only one ejection abnormality detection unit 10 is provided for each nozzle 110 of the plurality of inkjet heads 100a to 100e. The print data corresponding to each of the inkjet heads 100a to 100e is input from the host computer 8 to the ejection selection unit 182 through the control unit 6, and at the same time, the print data is specified by the scanning (selection) signal and Accordingly, only the switching unit 23 corresponding to the inkjet head 100 that performs the ejection driving operation performs the switching operation to detect the ejection abnormality of the corresponding inkjet head 100 and determine the cause thereof, so that a large amount of detection results can be obtained at one time. The load on the CPU 61 of the control unit 6 can be reduced without processing. Further, since the ejection abnormality detection unit 10 circulates the state of the nozzle separately from the ejection operation, it is possible to grasp the ejection abnormality for each nozzle even during drive printing, and to know the state of the nozzle 110 of the entire head unit 35. be able to. Accordingly, for example, since the ejection abnormality is regularly detected, it is possible to reduce the number of steps for detecting the ejection abnormality for each nozzle while the printing is stopped. From the above, it is possible to efficiently detect the ejection abnormality of the inkjet head 100 and determine the cause thereof.

Further, unlike the inkjet printer 1 shown in FIG. 28 or FIG. 29, the inkjet printer 1 shown in FIG. 30 needs to include only one ejection abnormality detection unit 10, and therefore the inkjet printer shown in FIGS. 28 and 29. 1, the circuit configuration of the inkjet printer 1 can be downscaled and an increase in the manufacturing cost thereof can be prevented.

Next, the operation of the printer 1 shown in FIGS. 27 to 30, that is, the ejection abnormality detection process (mainly detection timing) in the inkjet printer 1 including the plurality of inkjet heads 100 will be described. The ejection abnormality detection/determination processing (processing for multiple nozzles) detects residual vibration of the vibration plate 121 when the electrostatic actuator 120 of each inkjet head 100 performs an ink droplet ejection operation, and is based on the cycle of the residual vibration. Then, it is determined whether or not ejection abnormality (dot omission, ink droplet non-ejection) has occurred in the corresponding inkjet head 100, and if dot omission (ink droplet non-ejection) has occurred, what is the cause thereof. doing. As described above, if the ink jet head 100 ejects ink droplets (droplets), these detection/determination processes can be executed. However, the ink jet head 100 actually ejects ink droplets on the recording paper P. In addition to the case where the printing is performed, the flushing operation (preliminary ejection or preliminary ejection) may be performed.

Hereinafter, the ejection abnormality detection/determination processing (multi-nozzle) will be described for these two cases.
Here, the flushing (preliminary ejection) processing means that all of the head unit 35 or the head unit 35 is mounted when a cap (not shown in FIG. 1) is mounted or when ink droplets (droplets) are not applied to the recording paper P (media). This is a head cleaning operation of ejecting ink droplets from the target nozzle 110. This flushing process (flushing operation) is performed, for example, when the ink in the cavity 141 is periodically discharged in order to maintain the ink viscosity in the nozzle 110 within a proper range, or the ink thickening is performed. It is also performed as a time recovery operation. Further, the flushing process is also performed when ink is initially filled in each cavity 141 after the ink cartridge 31 is attached to the printing unit 3.

In addition, a wiping process for cleaning the nozzle plate (nozzle surface) 150 (a deposit (paper dust, dust, etc.) adhering to the head surface of the printing unit 3 is wiped with a wiper not shown in FIG. However, there is a possibility that the inside of the nozzle 110 will have a negative pressure and ink of another color (droplet of another type) will be drawn in. Therefore, after the wiping process, the flushing process is also performed in order to eject a fixed amount of ink droplets from all the nozzles 110 of the head unit 35. Further, the flushing process can be performed in a timely manner in order to maintain the meniscus state of the nozzle 110 normally and ensure good printing.

First, the ejection abnormality detection/determination processing during the flushing processing will be described with reference to the flowcharts shown in FIGS. Note that these flowcharts will be described with reference to the block diagrams of FIGS. 27 to 30 (hereinafter, the same applies during the printing operation). FIG. 31 is a flowchart showing the timing of ejection abnormality detection during the flushing operation of the inkjet printer 1 shown in FIG.

When the flushing process of the inkjet printer 1 is executed at a predetermined timing, the ejection abnormality detection/determination process shown in FIG. 31 is executed. The control unit 6 inputs the ejection data for one nozzle into the shift register 182a of the ejection selection unit 182 (step S401), inputs a latch signal into the latch circuit 182b (step S402), and latches this ejection data. .. At that time, the switching unit 23 connects the electrostatic actuator 120 of the inkjet head 100, which is the target of the ejection data, and the drive waveform generation unit 181 (step S403).

Then, the ejection abnormality detection unit 10 executes the ejection abnormality detection/determination processing shown in the flowchart of FIG. 24 for the inkjet head 100 that has performed the ink ejection operation (step S404). In step S405, the control unit 6 completes the ejection abnormality detection/determination processing for the nozzles 110 of all the inkjet heads 100a to 100e of the inkjet printer 1 shown in FIG. 27 based on the ejection data output to the ejection selection unit 182. Determine whether or not. When it is determined that these processes have not been completed for all the nozzles 110, the control unit 6 inputs the ejection data corresponding to the nozzles 110 of the next inkjet head 100 to the shift register 182a (step S406). The process proceeds to step S402 and the same processing is repeated.

When it is determined in step S405 that the above-described ejection abnormality detection and determination processing has been completed for all nozzles 110, the control unit 6 inputs the CLEAR signal to the latch circuit 182b, and the latch state of the latch circuit 182b. Is canceled, and the ejection abnormality detection/determination process in the inkjet printer 1 shown in FIG. 27 ends.

As described above, in the ejection abnormality detection/judgment processing in the printer 1 shown in FIG. 27, since the detection circuit is composed of one ejection abnormality detection means 10 and one switching means 23, the ejection abnormality detection processing and The determination process is repeated by the number of inkjet heads 100, but the circuit forming the ejection abnormality detection unit 10 does not become so large.

Next, FIG. 32 is a flowchart showing the timing of ejection abnormality detection during the flushing operation of the inkjet printer 1 shown in FIGS. 28 and 29. Although the ink jet printer 1 shown in FIG. 28 and the ink jet printer 1 shown in FIG. 29 have a slightly different circuit configuration, the numbers of the ejection abnormality detection means 10 and the switching means 23 correspond to the number of the ink jet heads 100 (the same). They agree on the points. Therefore, the ejection abnormality detection/determination process during the flushing operation includes the same steps.

When the flushing process of the inkjet printer 1 is executed at a predetermined timing, the control unit 6 inputs the ejection data for all nozzles to the shift register 182a of the ejection selection unit 182 (step S501) and latches it in the latch circuit 182b. A signal is input (step S502), and this ejection data is latched. At that time, the switching units 23a to 23e connect all the inkjet heads 100a to 100e and the drive waveform generation unit 181 (step S503).

The ejection abnormality detection/determination processing shown in the flowchart of FIG. 24 is performed in parallel for all the inkjet heads 100 that have performed the ink ejection operation by the ejection abnormality detection units 10a to 10e corresponding to the respective inkjet heads 100a to 100e. Are executed (step S504). In this case, the determination results corresponding to all the inkjet heads 100a to 100e are associated with the inkjet head 100 to be processed and stored in a predetermined storage area of the storage unit 62 (step S107 in FIG. 24).

Then, in order to clear the ejection data latched by the latch circuit 182b of the ejection selection unit 182, the control unit 6 inputs the CLEAR signal to the latch circuit 182b (step S505) to set the latch state of the latch circuit 182b. After canceling, the ejection abnormality detection process and the determination process in the inkjet printer 1 shown in FIGS. 28 and 29 are ended.

As described above, in the process in the printer 1 shown in FIGS. 28 and 29, the plurality (five in this embodiment) of the ejection abnormality detecting means 10 and the plurality of switching means 23 corresponding to the inkjet heads 100a to 100e are used. Since the detection and determination circuit is configured, the ejection abnormality detection/determination process can be executed for all the nozzles 110 at once in a short time.

Next, FIG. 33 is a flowchart showing the timing of ejection abnormality detection during the flushing operation of the inkjet printer 1 shown in FIG. Similarly, the ejection abnormality detection process and the cause determination process during the flushing operation will be described using the circuit configuration of the inkjet printer 1 shown in FIG.

When the flushing process of the inkjet printer 1 is executed at a predetermined timing, the control unit 6 first outputs a scanning signal to the switching selection unit (selector) 19a, and the switching selection unit 19a and the switching control unit 19 The first switching unit 23a and the inkjet head 100a are set (specified) (step S601). Then, the ejection data for all the nozzles is input to the shift register 182a of the ejection selection unit 182 (step S602), the latch signal is input to the latch circuit 182b (step S603), and the ejection data is latched. At that time, the switching unit 23a connects the electrostatic actuator 120 of the inkjet head 100a and the drive waveform generation unit 181 (step S604).

Then, the ejection abnormality detection/determination processing shown in the flowchart of FIG. 24 is executed on the inkjet head 100a that has performed the ink ejection operation (step S605). In this case, in step S103 of FIG. 24, the drive/detection switching signal which is the output signal of the switching selecting means 19a and the ejection data output from the latch circuit 182b are input to the AND circuit ANDa, and the output signal of the AND circuit ANDa. Becomes high level, the switching unit 23a connects the electrostatic actuator 120 of the inkjet head 100a and the ejection abnormality detection unit 10. Then, the determination result of the ejection abnormality determination process executed in step S106 of FIG. 24 is associated with the inkjet head 100 (here, 100a) to be processed and stored in a predetermined storage area of the storage unit 62. (Step S107 of FIG. 24).

In step S606, the control unit 6 determines whether or not the ejection abnormality detection/determination processing has been completed for all nozzles. When it is determined that the ejection abnormality detection/judgment processing has not been completed for all the nozzles 110, the control unit 6 outputs a scanning signal to the switching selection means (selector) 19a, and the switching selection means. The next switching unit 23b and the inkjet head 100b are set (identified) by 19a and the switching control unit 19 (step S607), the process proceeds to step S603, and the same processing is repeated. Hereinafter, this loop is repeated until the ejection abnormality detection/judgment processing is completed for all the inkjet heads 100.

If it is determined in step S606 that the ejection abnormality detection processing and the determination processing have been completed for all the nozzles 110, in order to clear the ejection data latched by the latch circuit 182b of the ejection selection unit 182, The control unit 6 inputs the CLEAR signal to the latch circuit 182b (step S609), releases the latched state of the latch circuit 182b, and ends the ejection abnormality detection process and the determination process in the inkjet printer 1 shown in FIG.

As described above, in the process in the inkjet printer 1 shown in FIG. 30, the detection circuit is composed of the plurality of switching means 23 and one ejection abnormality detection means 10, and is specified by the scanning signal of the switching selection means (selector) 19a, Since only the switching unit 23 corresponding to the inkjet head 100 that performs the ejection drive according to the ejection data performs the switching operation to perform the ejection abnormality detection and the cause determination of the corresponding inkjet head 100, the inkjet head is more efficient. It is possible to detect 100 discharge abnormalities and determine the cause.

Note that in step S602 of this flowchart, the discharge data corresponding to all the nozzles 110 is input to the shift register 182a, but as in the flowchart shown in FIG. 31, it is adjusted in the scanning order of the inkjet head 100 by the switching selection means 19a. Then, the ejection data input to the shift register 182a may be input to one corresponding inkjet head 100 to perform the ejection abnormality detection/determination processing for each nozzle 110.

Next, the ejection abnormality detection/determination processing of the inkjet printer 1 during the printing operation will be described with reference to the flowcharts shown in FIGS. 34 and 35. The inkjet printer 1 shown in FIG. 27 is mainly suitable for the ejection abnormality detection processing and the determination processing during the flushing operation, so the flowchart and the operation description thereof during the printing operation will be omitted. Also in the printer 1, the ejection abnormality detection/determination process may be performed during the printing operation.

FIG. 34 is a flowchart showing the timing of ejection abnormality detection during the printing operation of the inkjet printer 1 shown in FIGS. 28 and 29. The process of this flowchart is executed (started) by a print instruction from the host computer 8. When print data is input from the host computer 8 to the shift register 182a of the ejection selection unit 182 via the control unit 6 (step S701), a latch signal is input to the latch circuit 182b (step S702), and the print data is output. Latched. At this time, the switching units 23a to 23e connect all the inkjet heads 100a to 100e to the drive waveform generating unit 181 (step S703).

Then, the ejection abnormality detection unit 10 corresponding to the inkjet head 100 that has performed the ink ejection operation executes the ejection abnormality detection/determination processing shown in the flowchart of FIG. 24 (step S704). In this case, each determination result corresponding to each inkjet head 100 is associated with the inkjet head 100 to be processed and stored in a predetermined storage area of the storage unit 62.

Here, in the case of the inkjet printer 1 shown in FIG. 28, the switching means 23a to 23e cause the inkjet heads 100a to 100e to detect the ejection abnormality detection means 10a to 10e based on the drive/detection switching signal output from the control unit 6. 10e (step S103 in FIG. 24). Therefore, in the inkjet head 100 having no print data, since the electrostatic actuator 120 is not driven, the residual vibration detecting unit 16 of the ejection abnormality detecting unit 10 does not detect the residual vibration waveform of the diaphragm 121. On the other hand, in the case of the inkjet printer 1 shown in FIG. 29, the switching units 23a to 23e are ANDs to which the drive/detection switching signal output from the control unit 6 and the print data output from the latch circuit 182b are input. Based on the output signal of the circuit, the inkjet head 100 having print data is connected to the ejection abnormality detecting means 10 (step S103 in FIG. 24).

In step S705, the control unit 6 determines whether the printing operation of the inkjet printer 1 is completed. Then, when it is determined that the printing operation has not ended, the control unit 6 moves to step S701, inputs the next print data to the shift register 182a, and repeats the same processing. When it is determined that the printing operation has ended, the control unit 6 inputs the CLEAR signal to the latch circuit 182b in order to clear the ejection data latched by the latch circuit 182b of the ejection selection unit 182 (( In step S707), the latched state of the latch circuit 182b is released, and the ejection abnormality detection process and the determination process in the inkjet printer 1 shown in FIGS. 28 and 29 are ended.

As described above, the inkjet printer 1 shown in FIGS. 28 and 29 includes the plurality of switching units 23a to 23e and the plurality of ejection abnormality detection units 10a to 10e, and ejects all the inkjet heads 100 at once. Since the abnormality detection/determination process is performed, these processes can be performed in a short time. Further, the inkjet printer 1 shown in FIG. 29 further includes a switching control unit 19, that is, AND circuits ANDa to ANDe that perform a logical product operation of a drive/detection switching signal and print data, and only the inkjet head 100 that performs a printing operation. On the other hand, since the switching operation is performed by the switching unit 23, the ejection abnormality detection process and the determination process can be performed without performing unnecessary detection.

Next, FIG. 35 is a flowchart showing the timing of ejection abnormality detection during the printing operation of the inkjet printer 1 shown in FIG. According to a print instruction from the host computer 8, the process of this flowchart is executed in the inkjet printer 1 shown in FIG. First, the switching selection unit 19a sets (identifies) the first switching unit 23a and the inkjet head 100a in advance (step S801).

When print data is input from the host computer 8 via the control unit 6 to the shift register 182a of the ejection selection unit 182 (step S802), a latch signal is input to the latch circuit 182b (step S803), and the print data is output. Latched. At this stage, the switching means 23a to 23e connect all the inkjet heads 100a to 100e to the drive waveform generating means 181 (driver 182c of the ejection selecting means 182) (step S804).

When the inkjet head 100a has print data, the control unit 6 connects the post-ejection electrostatic actuator 120 to the ejection abnormality detection unit 10 by the switching selection unit 19a (step S103 in FIG. 24), and FIG. The ejection abnormality detection/determination processing shown in the flowchart of FIG. 25 is executed (step S805). Then, the determination result of the ejection abnormality determination process executed in step S106 of FIG. 24 is associated with the inkjet head 100 (here, 100a) to be processed and stored in a predetermined storage area of the storage unit 62. (Step S107 of FIG. 24).

In step S806, the control unit 6 determines whether or not the above-described ejection abnormality detection/determination processing has been completed for all nozzles 110 (all inkjet heads 100). When it is determined that the above processing has been completed for all the nozzles 110, the control unit 6 sets the switching means 23a corresponding to the first nozzle 110 based on the scanning signal (step S808), When it is determined that the above processing has not been completed for all the nozzles 110, the switching means 23b corresponding to the next nozzle 110 is set (step S807).

In step S809, the control unit 6 determines whether or not the predetermined printing operation instructed by the host computer 8 is completed. Then, when it is determined that the printing operation is not completed yet, the next print data is input to the shift register 182a (step S802), and the same processing is repeated. When it is determined that the printing operation is completed, the control unit 6 inputs the CLEAR signal to the latch circuit 182b in order to clear the ejection data latched by the latch circuit 182b of the ejection selection unit 182 (( (Step S811), the latched state of the latch circuit 182b is released, and the ejection abnormality detection/determination process in the inkjet printer 1 shown in FIG. 30 is ended.

As described above, the droplet discharge device (inkjet printer 1) of the present embodiment is configured such that the vibration plate 121, the electrostatic actuator 120 that displaces the vibration plate 121, and the inside of the liquid are filled with the vibration plate 121. An inkjet head (droplet) having a cavity 141 whose internal pressure is changed (increased/decreased) and a nozzle 110 which communicates with the cavity 141 and discharges liquid as a droplet by the change (increased/decreased) pressure in the cavity 141 A plurality of ejection heads 100 are provided, and a drive waveform generation unit 181 that drives these electrostatic actuators 120, and an ejection selection unit that selects from which nozzle 110 of the plurality of nozzles 110 a droplet is ejected. 182, one or more ejection abnormality detecting means 10 for detecting residual vibration of the vibration plate 121, and detecting abnormality of droplet ejection based on the detected residual vibration of the vibration plate 121, and electrostatic discharge One or more of switching the electrostatic actuator 120 from the drive waveform generation means 181 to the discharge abnormality detection means 10 based on a drive/detection switching signal, print data, or a scanning signal after a droplet discharge operation by driving the actuator 120. The switching means 23 of No. 1 is provided and the ejection abnormality of the plurality of nozzles 110 is detected once (in parallel) or sequentially.

Therefore, the ejection abnormality detection/determination method of the droplet ejection device and the droplet ejection head of the present embodiment can detect the ejection abnormality and the cause thereof in a short time, and the detection circuit including the ejection abnormality detection unit 10. It is possible to scale down the circuit configuration of, and it is possible to prevent an increase in the manufacturing cost of the droplet discharge device. In addition, after the electrostatic actuator 120 is driven, the discharge abnormality detection unit 10 is switched to perform discharge abnormality detection and cause determination, so that the drive of the actuator is not affected, thereby increasing the throughput of the droplet discharge device. Does not decrease or worsen. Further, it is also possible to equip the existing droplet discharge device (inkjet printer) provided with predetermined constituent elements with the discharge abnormality detection means 10.

Further, unlike the above-described configuration, the droplet discharge device of the present embodiment includes a plurality of switching means 23, a switching control means 19, and a plurality of discharge abnormality detecting means 10 corresponding to one or the number of nozzles 110. , Drive/detection switching signal and ejection data (print data), or based on the scanning signal, drive/detection switching signal and ejection data (print data), the corresponding electrostatic actuator 120 is driven by the drive waveform generation means 181 or ejection selection. The means 182 is switched to the discharge abnormality detection means 10 to detect the discharge abnormality and determine the cause.

Therefore, since the droplet ejection device of the present embodiment does not input ejection data (print data), that is, the switching unit corresponding to the electrostatic actuator 120 that is not performing the ejection driving operation does not perform the switching operation. Useless detection/judgment processing can be avoided. Further, when the switching selection means 19a is used, the droplet discharge device is required to include only one discharge abnormality detection means 10, so that the circuit configuration of the droplet discharge device can be scaled down. It is possible to prevent an increase in the manufacturing cost of the droplet discharge device.

Next, a configuration (recovery unit 24) that executes a recovery process for eliminating the cause of the ejection abnormality (head abnormality) for the inkjet head 100 (head unit 35) in the droplet ejection device of the present embodiment will be described. FIG. 36 is a diagram showing a schematic structure (partially omitted) as seen from above the inkjet printer 1 shown in FIG. The inkjet printer 1 shown in FIG. 36 includes a wiper 300 and a cap 310 for executing recovery processing of ink droplet non-ejection (head abnormality) in addition to the configuration shown in the perspective view of FIG.

As the recovery process performed by the recovery unit 24, a flushing process for preliminarily ejecting droplets from the nozzles 110 of each inkjet head 100, a wiping process by a wiper 300 (see FIG. 37) described later, and a tube pump 320 described later. The pumping process (pump suction process) is included. That is, the recovery means 24 includes a tube pump 320, a pulse motor for driving the tube pump 320, a wiper 300, a vertical drive mechanism for the wiper 300, and a vertical drive mechanism (not shown) for the cap 310, and in the flushing process. The head driver 33, the head unit 35, and the like, and the carriage motor 41 and the like function as a part of the recovery unit 24 in the wiping process. Since the flushing process has been described above, the wiping process and the pumping process will be described below.

Here, the wiping process is a process of wiping off foreign matter such as paper dust attached to the nozzle plate 150 (nozzle surface) of the head unit 35 with the wiper 300. The pumping process (pump suction process) is a process of driving the tube pump 320 described later to suck and discharge the ink in the cavity 141 from each nozzle 110 of the head unit 35. As described above, the wiping process is an appropriate process as a recovery process in the state of paper dust adhesion, which is one of the causes of the above-described droplet ejection abnormality of the inkjet head 100. The pump suction process removes air bubbles in the cavity 141 that cannot be removed by the flushing process described above, or when the ink in the vicinity of the nozzle 110 is dried or the ink in the cavity 141 is thickened due to aging deterioration. This is an appropriate process as a recovery process for removing viscous ink. When the viscosity has not increased so much and the viscosity is not so large, the recovery process by the flushing process described above may be performed. In this case, since the amount of ink discharged is small, it is possible to perform an appropriate recovery process without lowering the throughput or running cost.

The plurality of head units 35 are mounted on the carriage 32, guided by two carriage guide shafts 422, and connected to a timing belt 421 by a carriage motor 41 via a connecting portion 34 provided at the upper end of the drawing. Moving. The head unit 35 mounted on the carriage 32 is movable in the main scanning direction via a timing belt 421 which is driven by the carriage motor 41 (in synchronization with the timing belt 421). The carriage motor 41 plays a role of a pulley for continuously rotating the timing belt 421, and a pulley 44 is similarly provided on the other end side.

The cap 310 is for capping the nozzle plate 150 (see FIG. 5) of the head unit 35. A hole is formed in the bottom side surface of the cap 310, and a flexible tube 321 that is a component of the tube pump 320 is connected to the cap 310, as described later. The tube pump 320 will be described later in FIG. 39.

During the recording (printing) operation, while driving the electrostatic actuator 120 of the predetermined inkjet head 100 (droplet ejection head), the recording paper P moves in the sub-scanning direction, that is, downward in FIG. By moving in the main scanning direction, that is, right and left in FIG. 36, the inkjet printer (droplet ejecting device) 1 records a predetermined image or the like based on print data (print data) input from the host computer 8. Printing (recording) on the paper P.

FIG. 37 is a diagram showing the positional relationship between the wiper 300 shown in FIG. 36 and the printing means 3 (head unit 35). In FIG. 37, the head unit 35 and the wiper 300 are shown as a part of a side view of the inkjet printer 1 shown in FIG. As shown in FIG. 37A, the wiper 300 is arranged so as to be vertically movable so as to be able to contact the nozzle surface of the printing unit 3, that is, the nozzle plate 150 of the head unit 35.

Here, a wiping process which is a recovery process using the wiper 300 will be described. When performing the wiping process, as shown in FIG. 37A, the wiper 300 is moved upward by a driving device (not shown) so that the tip of the wiper 300 is located above the nozzle surface (nozzle plate 150). In this case, when the carriage motor 41 is driven to move the printing means 3 (head unit 35) to the left in the drawing (the direction of the arrow), the wiping member 301 comes into contact with the nozzle plate 150 (nozzle surface). Become.

Since the wiping member 301 is composed of a flexible rubber member or the like, as shown in FIG. 37(b), the tip portion of the wiping member 301 that comes into contact with the nozzle plate 150 is bent, and the tip portion causes the nozzle plate to contact. The surface of 150 (nozzle surface) is cleaned (wipe). As a result, it is possible to remove foreign matter such as paper dust (eg, paper dust, dust floating in the air, scraps of rubber, etc.) attached to the nozzle plate 150 (nozzle surface). Further, the wiping process can be performed a plurality of times by moving the printing unit 3 back and forth above the wiper 300 according to such a foreign substance adhesion state (when a large amount of foreign substances are adhered). ..

FIG. 38 is a diagram showing the relationship between the head unit 35, the cap 310, and the pump 320 during the pump suction process. The tube 321 forms an ink discharge path in the pumping process (pump suction process), one end of which is connected to the bottom of the cap 310 and the other end is discharged through the tube pump 320 as described above. It is connected to the ink cartridge 340.

An ink absorber 330 is arranged on the inner bottom surface of the cap 310. The ink absorber 330 absorbs the ink ejected from the nozzle 110 of the inkjet head 100 in the pump suction process or the flushing process and temporarily stores the ink. It should be noted that the ink absorber 330 can prevent the ejected droplets from bouncing back and contaminating the nozzle plate 150 during the flushing operation into the cap 310.

FIG. 39 is a schematic diagram showing the structure of the tube pump 320 shown in FIG. As shown in FIG. 39(B), the tube pump 320 is a rotary pump, and includes a rotating body 322, four rollers 323 arranged on the circumference of the rotating body 322, and a guide member 350. I have it. The roller 323 is supported by the rotating body 322, and presses the flexible tube 321 placed in an arc shape along the guide 351 of the guide member 350.

In this tube pump 320, one or two rollers 323 in contact with the tube 321 are rotated in the Y direction by rotating the rotating body 322 about the shaft 322a in the arrow X direction shown in FIG. 39. Meanwhile, the tube 321 placed on the arc-shaped guide 351 of the guide member 350 is sequentially pressurized. As a result, the tube 321 is deformed, and due to the negative pressure generated in the tube 321, the ink (liquid material) in the cavity 141 of each inkjet head 100 is sucked through the cap 310, and air bubbles are mixed in or dried. Unnecessary ink that has been thickened by is discharged to the ink absorber 330 via the nozzle 110, and the waste ink absorbed in this ink absorber 330 is discharged to the waste ink cartridge 340 (see FIG. 38) via the tube pump 320. Is discharged.

The tube pump 320 is driven by a motor such as a pulse motor (not shown). The pulse motor is controlled by the control unit 6. Drive information for the rotation control of the tube pump 320, for example, a look-up table in which the rotation speed and the rotation speed are described, a control program in which the sequence control is described, and the like are stored in the PROM 64 of the control unit 6 and the like. The tube pump 320 is controlled by the CPU 61 of the control unit 6 based on the drive information.

Next, the operation of the recovery means 24 (discharge abnormality recovery processing) will be described. FIG. 40 is a flowchart showing the ejection abnormality recovery process in the inkjet printer 1 (droplet ejection device). When the ejection abnormality nozzle 110 is detected in the above-described ejection abnormality detection/determination process (see the flowchart in FIG. 24) and the cause thereof is determined, printing is performed at a predetermined timing when no printing operation (printing operation) is performed. The means 3 is moved to a predetermined standby area (for example, a position where the nozzle plate 150 of the printing means 3 is covered with the cap 310 in FIG. 36, or a position where the wiping process by the wiper 300 can be performed), and the abnormal discharge recovery process is performed. To be executed.

First, the control unit 6 determines the determination result corresponding to each nozzle 110 stored in the EEPROM 62 of the control unit 6 in step S107 of FIG. 24 (here, this determination result is a determination result limited to each nozzle 110). However, it is not for each inkjet head 100. Therefore, in the following, the nozzle 110 having an ejection abnormality also refers to the inkjet head 100 in which the ejection abnormality has occurred (step S901). In step S902, the control unit 6 determines whether or not the read determination result includes the nozzle 110 with the ejection abnormality. Then, if it is determined that there is no abnormal ejection nozzle 110, that is, if droplets have been ejected normally from all the nozzles 110, then this ejection abnormality recovery processing is ended.

On the other hand, if it is determined that any one of the nozzles 110 has an ejection abnormality, then in step S903, the control unit 6 determines whether or not the nozzle 110 determined to have the ejection abnormality has adhered paper dust. .. If it is determined that the paper dust does not adhere to the vicinity of the outlet of the nozzle 110, the process proceeds to step S905, and if it is determined that the paper dust adheres, the wiper 300 described above is used. Wiping processing for the nozzle plate 150 is executed (step S904).

In step S905, subsequently, the control unit 6 determines whether or not the nozzle 110, which has been determined to have the ejection abnormality, contains air bubbles. When it is determined that the air bubbles are mixed, the control unit 6 executes the pump suction process by the tube pump 320 for all the nozzles 110 (step S906), and ends the discharge abnormality recovery process. On the other hand, when it is determined that the air bubbles are not mixed, the control unit 6 determines whether or not the tube pump 320 performs the pump suction process or the discharge abnormality based on the length of the cycle of the residual vibration of the diaphragm 121 measured by the measuring unit 17. Flushing processing is executed for only the nozzles 110 that have been determined to be “NO” or for all nozzles 110 (step S907), and this ejection abnormality recovery processing ends.

The pump suction recovery process, which is one of the recovery processes executed by the recovery unit 24, is effective for the case where the viscosity is increased due to drying or the like and the case where bubbles are mixed, and the same is true for any cause. Therefore, when the inkjet head 100 of the air bubble mixing and the dry thickening which needs the pump suction processing is detected in the head unit, the ink jet head 100 is individually detected as in steps S905 to S907 in the flowchart of FIG. The pump suction processing may be executed at once for the inkjet head 100 containing air bubbles and the inkjet head 100 for dry thickening without determining the processing. That is, after determining whether or not the paper powder is attached to the vicinity of the nozzle 110, the pump suction process may be executed without determining whether air bubbles are mixed or the viscosity is increased by drying.

FIG. 41 is a diagram for explaining another configuration example (wiper 300′) of the wiper (wiping means), and (a) shows the nozzle surface (nozzle plate 150) of the printing means 3 (head unit 35). FIG. 3B is a view showing the wiper 300′. 42 is a diagram showing an operating state of the wiper 300' shown in FIG.

Hereinafter, a wiper 300' which is another example of the configuration of the wiper will be described based on these drawings, but the description will be focused on the differences from the wiper 300 described above, and the description of the same matters will be omitted.

As shown in FIG. 41A, on the nozzle surface of the printing unit 3, the plurality of nozzles 110 correspond to inks of yellow (Y), magenta (M), cyan (C), and black (K). And is divided into four nozzle groups. With the configuration described below, the wiper 300' of the present configuration example is capable of performing wiping processing for each of the four nozzle groups separately for each color nozzle group.

As shown in FIG. 41( b ), the wiper 300 ′ includes a wiping member 301 a for the yellow nozzle group, a wiping member 301 b for the magenta nozzle group, a wiping member 301 c for the cyan nozzle group, and a black wiping member 301 c. It has a wiping member 301d for the nozzle group. As shown in FIG. 42, the wiping members 301a to 301d can be independently moved in the sub-scanning direction by a moving mechanism (not shown).

The wiper 300 described above collectively performs the wiping process on the nozzle surfaces of all the nozzles 110. However, according to the wiper 300′ of the present configuration example, only the nozzle group that requires the wiping process is wiped. Therefore, recovery processing can be performed without waste.

FIG. 43 is a diagram for explaining another configuration example of the pumping means. Hereinafter, another configuration example of the pumping means will be described with reference to this drawing, but the description will be focused on the differences from the pumping means described above, and the description of the same matters will be omitted.

As shown in FIG. 43, the pumping means of this configuration example includes a cap 310a for a yellow nozzle group, a cap 310b for a magenta nozzle group, a cap 310c for a cyan nozzle group, and a black nozzle group. Cap 310d.

The tube 321 of the tube pump 320 is branched into four branch tubes 325a to 325d, and the branch tubes 325a to 325d are connected to the caps 310a to 310d, respectively. Valves 326a to 326d are provided in the middle of the respective branch tubes 325a to 325d.

The pumping means of the present configuration example as described above selects the opening and closing of each of the valves 326a to 326d so that the four groups of nozzles of the printing means 3 are pumped separately for each nozzle group of each color. You can do it. As a result, only the nozzle group that needs the pump suction process can be sucked, so that the recovery process can be performed without waste. Although FIG. 43 shows an example in which the tube pump 320 is sucking with the same tubes 321 for four colors, the tubes for the four colors may be separately provided in the tube pump 320.

By the way, the inkjet printer 1 as described above operates in the following flow when the ejection abnormality detecting unit 10 detects all the nozzles 110. Hereinafter, in the inkjet printer 1, two patterns will be sequentially described with respect to the flow of operations after that when the ejection abnormality detection unit 10 detects the first pattern.

[1A]
In the inkjet printer 1, during the flushing process (flushing operation) or the printing operation, the ejection abnormality detecting unit 10 detects all the nozzles 110 as described above.

As a result of this detection, when there is a nozzle 110 (hereinafter, referred to as “abnormal nozzle”) in which an ejection abnormality has occurred, it is preferable that the inkjet printer 1 informs that effect. The means (method) of this notification is not particularly limited, and for example, it is displayed on the operation panel 7, a sound, an alarm sound, a lamp is turned on, or via the interface 9 to the host computer 8 or the like, or Anything may be used, such as one that transmits ejection abnormality information to a print server or the like via a network.

[2A]
As a result of the detection in [1A], when there is a nozzle 110 (abnormal nozzle) in which an ejection abnormality has occurred (when the printing operation is in progress, the printing operation is interrupted), the recovery processing by the recovery means 24 is performed. .. In this case, the recovery unit 24 performs a recovery process of a type corresponding to the cause of the abnormal discharge of the abnormal nozzle, as in the flowchart of FIG. 40 described above. As a result, for example, when the cause of the discharge abnormality of the abnormal nozzle is the adherence of paper dust, that is, the pump suction process is not performed even when the pump suction process does not need to be performed, the ink is wasted. It is possible to prevent the ink from being discharged to the ink, and it is possible to reduce the amount of ink consumed. Moreover, since the unnecessary type of recovery process is not performed, the time required for the recovery process can be shortened and the throughput of the inkjet printer 1 (the number of printed sheets per unit time) can be improved.

The recovery process may be performed on all the nozzles 110, but may be performed on at least the abnormal nozzles. For example, when performing the flushing process as the recovery process, the flushing operation may be performed only on the abnormal nozzle. Further, when the wiping means or the pumping means is configured to be able to perform recovery processing separately for each nozzle group of each color as shown in FIGS. 41 to 43, the abnormal nozzle detected in [1A] is detected. The wiping process or the pump suction process may be performed only on the nozzle group that includes it.

Further, in [1A], when a plurality of abnormal nozzles with different causes of ejection abnormality are detected, it is preferable to perform a plurality of types of recovery processing so as to eliminate all the causes of ejection abnormality.

[3A]
When the recovery process of [2A] is completed, the droplet discharge operation is performed only on the abnormal nozzle detected in [1A], and the abnormal discharge nozzle 10 detects again only this abnormal nozzle. This makes it possible to confirm whether or not the abnormal nozzle detected in [1A] has recovered to the normal state, so that it is possible to more reliably prevent the occurrence of ejection abnormality in the subsequent printing operation.

Further, here, since the ejection abnormality detecting means 10 performs the detection by causing only the abnormal nozzle to perform the droplet ejection operation, it is not necessary to eject the ink droplet from the nozzle 110 that was normal in [1A]. Therefore, it is possible to avoid wasteful ejection of ink, and it is possible to reduce the amount of ink consumption. Further, the load on the discharge abnormality detecting unit 10 and the control unit 6 can be reduced.

In addition, when there is a nozzle 110 having an abnormal ejection even by the detection in [3A], it is preferable to perform the recovery process by the recovery unit 24 again.
Hereinafter, in the inkjet printer 1, the second pattern of the operation flow after that when the ejection abnormality detection unit 10 performs the detection will be described. That is, in the present embodiment, instead of the above [1A] to [3A], control may be performed according to the following flow [1B] to [5B].

[1B]
Similar to the above [1A], the ejection abnormality detection unit 10 detects all the nozzles 110.

[2B]
As a result of the detection in [1B], when there is a nozzle 110 (hereinafter, referred to as “abnormal nozzle”) in which an ejection abnormality has occurred (when the printing operation is in progress, the printing operation is interrupted), the abnormality The flushing process is executed only for the nozzle. When the cause of the ejection abnormality of the abnormal nozzle is slight, the flushing process can restore the abnormal nozzle to a normal state. Further, at this time, since the ink droplets are not ejected from the normal nozzles 110, the ink is not wastefully consumed. Since the cause of the discharge abnormality is often small when the discharge abnormality detection means 10 frequently performs detection, the flushing process is first performed on the abnormal nozzle regardless of the cause of the discharge abnormality. Thus, the recovery process can be performed efficiently and quickly.

[3B]
After the flushing process of [2B] is completed, the droplet discharge operation is performed only on the abnormal nozzle detected in [1B], and the abnormal discharge nozzle 10 detects again only the abnormal nozzle. This makes it possible to confirm whether or not the abnormal nozzle detected in [1B] has recovered to the normal state, so that it is possible to more reliably prevent occurrence of ejection abnormality in the subsequent printing operation.

Further, here, since only the abnormal nozzle is caused to perform the liquid droplet ejection operation and the ejection abnormality detection means 10 performs the detection, it is not necessary to eject the ink droplet from the nozzle 110 which is normal in [1B]. Therefore, it is possible to avoid wasteful ejection of ink, and it is possible to reduce the amount of ink consumption. Further, the load on the discharge abnormality detecting unit 10 and the control unit 6 can be reduced.

[4B]
As a result of the detection in [3B], if there is a nozzle 110 (hereinafter, referred to as “re-abnormal nozzle”) in which the ejection abnormality has not been eliminated, the recovery means 24 performs the recovery process. In this case, the recovery means 24 performs a recovery process of a type corresponding to the cause of the abnormal discharge of the re-abnormal nozzle, as in the flowchart of FIG. 40 described above. Accordingly, for example, when the cause of the abnormal discharge of the re-abnormal nozzle is the adherence of paper dust, that is, the pump suction process is not performed even when the pump suction process does not need to be performed, the ink is not collected. It is possible to prevent wasteful discharge, and it is possible to reduce ink consumption. Moreover, since the unnecessary type of recovery process is not performed, the time required for the recovery process can be shortened and the throughput of the inkjet printer 1 (the number of printed sheets per unit time) can be improved.

Further, since the flushing process is performed in [2B], it is preferable to perform the recovery process other than that in [4B]. That is, if the cause of the discharge abnormality of the re-abnormal nozzle is air bubble inclusion or dry thickening, the pump suction process is executed, and if the paper dust is attached, the wiping process by the wiper 300 or 300′ is executed. Is preferred.

Note that this [4B] is the same as the above [2A] except for the above points.
[5B]
When the recovery process of [4B] is completed, the droplet ejection operation is performed only on the re-abnormal nozzle detected in [3B], and the ejection abnormality detection unit 10 performs the detection again only for this re-abnormal nozzle. This makes it possible to confirm whether or not the re-abnormal nozzle detected in [3B] has recovered to a normal state, and thus it is possible to more reliably prevent the occurrence of ejection abnormality in the subsequent printing operation. ..

Further, here, since only the re-abnormal nozzle performs the droplet ejection operation and the ejection abnormality detection unit 10 performs the detection, the ink droplet is not ejected from the nozzle 110 which is normal in [1B] and [3B]. I'm done. Therefore, it is possible to avoid wasteful ejection of ink, and it is possible to reduce the amount of ink consumption. Further, the load on the discharge abnormality detecting unit 10 and the control unit 6 can be reduced.

In [1A] to [3A] and [1B] to [5B] described above, after performing the recovery process according to the cause of the ejection abnormality, the flushing process is performed on each nozzle 110 (all nozzles 110). Preferably. Accordingly, it is possible to prevent the inks of the respective colors remaining on the nozzle surface (nozzle plate 150) from being mixed, and it is possible to prevent the inks from being mixed.

As described above, the droplet discharge device according to the present embodiment does not require any other component (for example, an optical dot dropout detection device) as compared with the conventional droplet discharge device capable of detecting an abnormal discharge. Therefore, it is possible to detect a droplet discharge abnormality without increasing the size of the droplet discharge head, and it is possible to reduce the manufacturing cost of the droplet discharge device that can detect a discharge abnormality (dot omission). it can. Further, since the droplet ejection abnormality is detected using the residual vibration of the vibration plate after the droplet ejection operation, it is possible to detect the droplet ejection abnormality even during the recording operation.

<Second Embodiment>
Next, another configuration example of the inkjet head will be described. 44 to 47 are cross-sectional views schematically showing another configuration example of the inkjet head (head unit). Hereinafter, description will be given based on these drawings, but the description will be centered on points that are different from the above-described embodiment, and description of similar matters will be omitted.

In the inkjet head 100A shown in FIG. 44, the vibration plate 212 vibrates by driving the piezoelectric element 200, and the ink (liquid) in the cavity 208 is ejected from the nozzle 203. A stainless steel nozzle plate 202 having nozzles (holes) 203 formed therein is joined with a stainless steel metal plate 204 via an adhesive film 205, and a similar stainless steel metal plate is further formed thereon. 204 is joined via an adhesive film 205. Then, the communication port forming plate 206 and the cavity plate 207 are sequentially joined thereon.

The nozzle plate 202, the metal plate 204, the adhesive film 205, the communication port forming plate 206, and the cavity plate 207 are each formed in a predetermined shape (a shape in which a recess is formed), and by overlapping these, the cavity 208 and A reservoir 209 is formed. The cavity 208 and the reservoir 209 communicate with each other through the ink supply port 210. Further, the reservoir 209 communicates with the ink intake port 211.

A vibrating plate 212 is installed in the upper opening of the cavity plate 207, and a piezoelectric element (piezo element) 200 is bonded to the vibrating plate 212 via a lower electrode 213. An upper electrode 214 is joined to the side of the piezoelectric element 200 opposite to the lower electrode 213. The head drive 215 includes a drive circuit that generates a drive voltage waveform, and by applying (supplying) the drive voltage waveform between the upper electrode 214 and the lower electrode 213, the piezoelectric element 200 vibrates and is bonded thereto. The diaphragm 212 vibrates. The vibration of the vibrating plate 212 changes the volume of the cavity 208 (pressure inside the cavity), and the ink (liquid) filled in the cavity 208 is ejected as droplets from the nozzle 203.

The amount of liquid reduced in the cavity 208 due to the ejection of droplets is supplied by supplying ink from the reservoir 209. Further, ink is supplied to the reservoir 209 from the ink intake port 211.

In the ink jet head 100B shown in FIG. 45, similarly to the above, the ink (liquid) in the cavity 221 is ejected from the nozzle by driving the piezoelectric element 200. The inkjet head 100B has a pair of substrates 220 facing each other, and a plurality of piezoelectric elements 200 are intermittently installed between the substrates 220 at predetermined intervals.

A cavity 221 is formed between the adjacent piezoelectric elements 200. A plate (not shown) is installed on the front side of the cavity 221 in FIG. 45, and a nozzle plate 222 is installed on the rear side thereof, and nozzles (holes) 223 are formed at positions corresponding to the respective cavities 221 of the nozzle plate 222. ..

A pair of electrodes 224 is provided on one surface and the other surface of each piezoelectric element 200, respectively. That is, the four electrodes 224 are bonded to one piezoelectric element 200. By applying a predetermined drive voltage waveform between predetermined electrodes of these electrodes 224, the piezoelectric element 200 is deformed in the shear mode and vibrates (indicated by an arrow in FIG. 45), and the volume of the cavity 221 ( The pressure in the cavity) changes, and the ink (liquid) filled in the cavity 221 is ejected from the nozzle 223 as a droplet. That is, in the inkjet head 100B, the piezoelectric element 200 itself functions as a diaphragm.

In the inkjet head 100C shown in FIG. 46, similarly to the above, the ink (liquid) in the cavity 233 is ejected from the nozzle 231 by driving the piezoelectric element 200. The inkjet head 100C includes a nozzle plate 230 having a nozzle 231, a spacer 232, and a piezoelectric element 200. The piezoelectric element 200 is installed at a predetermined distance from the nozzle plate 230 via a spacer 232, and a cavity 233 is formed in a space surrounded by the nozzle plate 230, the piezoelectric element 200, and the spacer 232.

A plurality of electrodes are joined to the upper surface of the piezoelectric element 200 in FIG. 46. That is, the first electrode 234 is bonded to the substantially central portion of the piezoelectric element 200, and the second electrodes 235 are bonded to both side portions thereof. By applying a predetermined drive voltage waveform between the first electrode 234 and the second electrode 235, the piezoelectric element 200 deforms in shear mode and vibrates (indicated by an arrow in FIG. 46), and this vibration causes the cavity 233 to move. The volume (pressure in the cavity) changes, and the ink (liquid) filled in the cavity 233 is ejected as droplets from the nozzle 231. That is, in the inkjet head 100C, the piezoelectric element 200 itself functions as a diaphragm.

In the ink jet head 100D shown in FIG. 47, the ink (liquid) in the cavity 245 is ejected from the nozzle 241 by the driving of the piezoelectric element 200, similarly to the above. The inkjet head 100D includes a nozzle plate 240 having nozzles 241, a cavity plate 242, a vibration plate 243, and a laminated piezoelectric element 201 formed by laminating a plurality of piezoelectric elements 200.

The cavity plate 242 is molded into a predetermined shape (a shape in which a recess is formed), whereby the cavity 245 and the reservoir 246 are formed. The cavity 245 and the reservoir 246 communicate with each other via the ink supply port 247. Further, the reservoir 246 communicates with the ink cartridge 31 via the ink supply tube 311.

The lower end of the laminated piezoelectric element 201 in FIG. 47 is joined to the vibration plate 243 via the intermediate layer 244. A plurality of external electrodes 248 and internal electrodes 249 are joined to the laminated piezoelectric element 201. That is, the external electrode 248 is bonded to the outer surface of the laminated piezoelectric element 201, and the internal electrode 249 is provided between the piezoelectric elements 200 forming the laminated piezoelectric element 201 (or inside each piezoelectric element). ing. In this case, the external electrodes 248 and some of the internal electrodes 249 are alternately arranged so as to overlap each other in the thickness direction of the piezoelectric element 200.

Then, by applying a drive voltage waveform from the head driver 33 between the external electrode 248 and the internal electrode 249, the laminated piezoelectric element 201 is deformed as shown by the arrow in FIG. 47 (expandable in the vertical direction in FIG. 47). Then, the vibration causes the diaphragm 243 to vibrate. The vibration of the vibrating plate 243 changes the volume of the cavity 245 (pressure inside the cavity), and the ink (liquid) filled in the cavity 245 is ejected from the nozzle 241 as a droplet.

The amount of liquid reduced in the cavity 245 due to the ejection of droplets is supplied by supplying ink from the reservoir 246. Ink is supplied from the ink cartridge 31 to the reservoir 246 via the ink supply tube 311.

In the inkjet heads 100A to 100D provided with the above-described piezoelectric elements, droplet ejection is performed based on the residual vibration of the vibration plate or the piezoelectric element functioning as the vibration plate, similarly to the above-described electrostatic capacity type inkjet head 100. Can be detected or the cause of the abnormality can be specified. In the inkjet heads 100B and 100C, a vibration plate (a vibration plate for detecting residual vibration) as a sensor may be provided at a position facing the cavity and the residual vibration of the vibration plate may be detected. ..

<Third Embodiment>
Next, still another configuration example of the inkjet head will be described. 48 is a perspective view showing the configuration of the head unit 35 in the present embodiment, and FIG. 49 is a sectional view of the head unit 35 (inkjet head 100H) shown in FIG. Hereinafter, description will be given based on these drawings, but the description will be centered on points that are different from the above-described embodiment, and description of similar matters will be omitted.

The head unit 35 (inkjet head 100H) shown in FIGS. 48 and 49 is of a so-called film boiling inkjet system (thermal jet system), and includes a support plate 410, a substrate 420, an outer wall 430 and a partition wall 431, and a top plate 440. And are joined in this order from the lower side in FIGS. 48 and 49.

The substrate 420 and the top plate 440 are installed at a predetermined interval through the outer wall 430 and a plurality of (six in the illustrated example) partition walls 431 arranged in parallel at equal intervals. A plurality of (five in the illustrated example) cavities (pressure chambers: ink chambers) 141 defined by partition walls 431 are formed between the substrate 420 and the top plate 440. Each cavity 141 has a strip shape (a rectangular parallelepiped shape).

Further, as shown in FIGS. 48 and 49, the left end portion (upper end in FIG. 48) of each cavity 141 in FIG. 49 is covered with a nozzle plate (front plate) 433. The nozzle (hole) 110 communicating with each cavity 141 is formed in the nozzle plate 433, and ink (liquid material) is ejected from the nozzle 110.

In FIG. 48, the nozzles 110 are arranged linearly with respect to the nozzle plate 433, that is, in a row, but it goes without saying that the arrangement pattern of the nozzles is not limited to this.
The nozzle plate 433 may not be provided, and the upper end (left end in FIG. 49) of each cavity 141 in FIG. 48 may be opened, and the opened opening may serve as a nozzle.

An ink intake port 441 is formed in the top plate 440, and the ink intake port 441 is connected to the ink cartridge 31 via an ink supply tube 311.

A heating element 450 is installed (embedded) at a location corresponding to each cavity 141 of the substrate 420. Each heating element 450 is separately energized by the head driver (energizing means) 33 including the drive circuit 18 to generate heat. The head driver 33 outputs, for example, a pulse signal as a drive signal for the heating element 450 according to a print signal (print data) input from the control unit 6.

The surface of the heating element 450 on the side of the cavity 141 is covered with a protective film (anti-cavitation film) 451. The protective film 451 is provided to prevent the heating element 450 from directly contacting the ink in the cavity 141. By providing the protective film 451, it is possible to prevent the deterioration and deterioration of the heating element 450 due to contact with the ink.

Recesses 460 are formed on the substrate 420 in the vicinity of each heating element 450 and at a location corresponding to each cavity 141. The recess 460 can be formed by a method such as etching or punching.

A diaphragm (diaphragm) 461 is installed so as to shield the cavity 141 side of the recess 460. The vibrating plate 461 elastically deforms (elastically displaces) in the up-down direction in FIG. 49 following the change in the pressure (liquid pressure) in the cavity 141.

This diaphragm 461 also functions as an electrode. The diaphragm 461 may be entirely conductive, or may be a stack of a conductive layer and an insulating layer.
On the other hand, the other side of the concave portion 460 is covered with a support plate 410, and electrodes (segment electrodes) 462 are installed on the upper surface of the support plate 410 in FIG. 49 corresponding to the respective vibration plates 461. Has been done.

The vibration plate 461 and the electrode 462 are arranged so as to face each other substantially in parallel with a predetermined gap distance.
In this way, by disposing the diaphragm 461 and the electrode 462 with a slight distance therebetween, it is possible to form a parallel plate capacitor. When the diaphragm 461 follows the pressure in the cavity 141 and is elastically displaced (deformed) in the vertical direction in FIG. 49, the gap distance between the diaphragm 461 and the electrode 462 changes accordingly, and the parallel plate The capacitance of the capacitor changes. In the inkjet head 100H, the vibrating plate 461 and the electrode 462 function as a sensor that detects an abnormality of the inkjet head 100H based on a temporal change in the capacitance due to vibration (residual vibration (damping vibration)) of the vibrating plate 461. To do.

A common electrode 470 is formed outside the cavity 141 of the substrate 420. A segment electrode 471 is formed outside the cavity 141 of the support plate 410. The electrode 462, the common electrode 470, and the segment electrode 471 can be formed by methods such as metal foil bonding, plating, vapor deposition, and sputtering.

Each diaphragm 461 and the common electrode 470 are electrically connected by a conductor 475, and each electrode 462 and each segment electrode 471 are electrically connected by a conductor 476.
As the conductors 475 and 476, [1] a conductor wire such as a metal wire is provided, and [2] a thin film made of a conductive material such as gold or copper is formed on the surface of the substrate 420 or the support plate 410. Or [3] a substrate 420 or the like in which a conductor forming portion is subjected to ion doping or the like to impart conductivity.

Next, the operation (operating principle) of the inkjet head 100H will be described.
When a drive signal (pulse signal) is output from the head driver 33 and the heating element 450 is energized, the heating element 450 instantly generates heat at a temperature of 300° C. or higher. As a result, bubbles 480 (different from the bubbles generated and mixed in the cavity causing the discharge abnormality described above) 480 are generated on the protective film 451 due to film boiling, and the bubbles 480 instantly expand. As a result, the liquid pressure of the ink (liquid material) filled in the cavity 141 increases, and a part of the ink is ejected from the nozzle 110 as a droplet.

The amount of liquid reduced in the cavity 141 due to the ejection of ink droplets is supplied by supplying new ink from the ink intake port 441 into the cavity 141. This ink is supplied from the ink cartridge 31 through the inside of the ink supply tube 311.

Immediately after the ink droplet is discharged, the bubble 480 contracts sharply and returns to the original state. The vibration plate 461 is elastically displaced (deformed) by the pressure change in the cavity 141 at this time, and damping vibration (residual vibration) occurs until the next drive signal is input and ink droplets are ejected again. .. When the vibration plate 461 generates damping vibration, the capacitance of the capacitor formed by the vibration plate 461 and the electrode 462 facing the vibration plate 461 changes accordingly. In the inkjet head 100H of the present embodiment, the discharge abnormality can be detected by utilizing the temporal change of the electrostatic capacitance, similarly to the inkjet head 100 of the first embodiment described above.

<Fourth Embodiment>
Since the hardware configuration of the fourth embodiment is the same as that of the first embodiment, the description thereof will be omitted. FIG. 50 is a table showing print modes prepared in the fourth embodiment. As shown in FIG. 50, in the fourth embodiment, "highest image quality", "high speed image quality", "normal", and "high speed draft" modes are prepared as print modes. As shown in FIG. 50, the waveforms (A) to (D) are selected in these modes. This waveform is a latch signal and a drive waveform generated by the drive waveform generation means 181.

FIG. 51 shows a waveform (A) selected in the highest image quality mode and a waveform (B) selected in the high speed image quality mode. When the waveform (A) is selected, the signal COM1 as the drive waveform and the signal LAT1 as the latch signal are selected. When the waveform (B) is selected, the signal COM2 as the drive waveform and the signal LAT2 as the latch signal are selected.

As shown in FIG. 50, when the waveform (A) is selected, the discharge amount for each section is (12+8+0) ng, and the maximum discharge amount is 20 ng. The maximum discharge amount coincides with the total value of discharge amounts for each classification. The division in the ejection amount for each division is a division of the signal COM1 that can be divided by the channel signal CH. The first section is defined by the rising edge LATa of the signal LAT1 shown in FIG. 50 to the rising edge CHa of the channel signal CH. The second section is defined by CHa shown in FIG. 50 to another rising edge CHa' of the channel signal CH. The third section is defined by CHa' shown in FIG. 50 to another rising edge LATa' of LAT1.

The ejection amount of 12+8+0 (ng) for each section means that ink is not ejected in the third section. In this section, the abnormality detection described in the first embodiment is performed. Hereinafter, in the third section of the signal COM1, a portion having a potential higher than the intermediate potential is referred to as a "test waveform".

As shown in FIG. 51, the difference between COM1 and COM2 is the voltage value and the length of time of the inspection waveform (hereinafter referred to as “inspection time”). The voltage value of the inspection waveform of COM1 is voltage V1, and the voltage value of the inspection waveform of COM2 is voltage V2 (<voltage V1). The inspection time of COM1 is t1, and the inspection time of COM2 is t2 (=t1−Δt). As shown in FIG. 51, Δt is equal to the difference obtained by subtracting the period of LAT2 from the period of LAT1 (time from LATa to LATa′). The fact that the cycle of LAT1 is longer than that of LAT2 means that the highest settable frequency (10/s) in the highest image quality mode is higher than the highest settable frequency (14.8/s) in the high speed image quality mode. It is also shown by being small. The highest settable frequency is the highest value of the nozzle drive frequency. Since the maximum settable frequency is different, the main scanning speed of the printing unit 3 in the highest image quality mode is slower than the main scanning speed of the printing unit 3 in the high image quality mode, as shown in FIG. The difference between the maximum settable frequency and the main scanning speed corresponds to the fact that the printing speed in the highest image quality mode is slower than the printing speed in the high speed and high image quality mode.

As described above, the highest image quality mode has a merit that the residual vibration can be reduced because the voltage value of the inspection waveform is lower than that of the high speed high image quality mode, and the time for which the residual vibration can be detected can be set particularly long. On the other hand, there is a merit that it is possible to obtain detailed information in particular, but on the other hand, there is a demerit that high-speed driving cannot be performed because the driving frequency becomes small.

FIG. 52 shows a waveform (C) selected in the normal mode and a waveform (D) selected in the high speed draft mode. When the waveform (C) is selected, the drive waveform COM3 and the latch signal LAT3 are selected. When the waveform (D) is selected, COM4 as the drive waveform and the signal LAT4 as the latch signal are selected.

As shown in FIG. 50, when the waveform (C) is selected, the discharge amount for each section is (12+8+12) ng, and the maximum discharge amount is 32 ng. The ejection amount of 12 ng in the third section means that the ejection of ink is performed together with the abnormality detection by the inspection waveform.

As shown in FIG. 50, when the waveform (D) is selected, the discharge amount for each section is 12+8+8 (ng), and the maximum discharge amount is 28 ng. The ink discharge amount in the inspection waveform is smaller than that in the case of the waveform (C), as shown in FIG. 52, when the voltage value of the inspection waveform is in the waveform of the waveform (C) (voltage V3). This is because the case (D) (voltage V4) is smaller.

As described above, in the high-speed draft mode, the voltage of the inspection waveform is lower than in the normal mode, and therefore, there is an advantage that the influence of the residual vibration after the inspection is small. There is a demerit that the detection signal obtained from the residual vibration after driving the piezo element 200 may not be output correctly and may cause an erroneous detection because it may not be sufficient.

As shown in FIG. 52, COM3 and COM4 differ from each other in inspection time in addition to the voltage value described above. The inspection time of COM3 is t3, and the inspection time of COM4 is t4 (=t3-Δt'). Δt′ is equal to the difference obtained by subtracting the period of LAT4 from the period of LAT3, as shown in FIG. The fact that the cycle of LAT3 is longer than that of LAT4 means that the maximum settable frequency (1/s) in FIG. 50 is the value in the normal mode (9.8/s) and the value in the high speed draft mode ( Smaller than 10.2/s). Since the maximum settable frequency is different in this way, as shown in FIG. 50, the main scanning speed of the printing unit 3 in the normal mode is slower than the main scanning speed of the printing unit 3 in the high speed draft mode. The difference between the maximum settable frequency and the main scanning speed corresponds to the fact that the printing speed in the normal mode is slower than that in the high speed draft mode.

As described above, since the inspection time is different, the inspection time can be set longer in the normal mode than in the high speed draft mode, so that there is an advantage that detailed information of the nozzle can be obtained.

By the way, the voltages V3 and 4 have a larger value than the voltages V1 and V2 in order to realize ink ejection. Therefore, the signals COM3 and 4 have the vibration suppression waveform after the inspection waveform. The vibration damping waveform is for suppressing the vibration of the meniscus caused by the inspection waveform.

Comparing the highest image quality mode and the high speed image quality mode, which are generally provided as the print mode, and the normal mode and the high speed draft mode, there are the following differences. Compared to the normal mode and the high-speed draft mode, the highest image quality mode and the high-speed high-quality mode have the advantage that abnormalities can be detected without ejecting ink, and the vibration suppression waveform is unnecessary, so the inspection time can be set longer. Therefore, there is an advantage that detailed information of the nozzle can be obtained. On the other hand, since the driving amount of the piezo element 200 at the time of abnormality detection is small, the detection signal obtained from the residual vibration after driving the piezo element 200 is correct. There is a demerit that there is a risk of not being output and causing false detection.

On the other hand, the normal mode and the high-speed draft mode have the merit of being able to print and detect abnormalities at a higher speed than the highest image quality mode and the high-speed image quality mode, and the merit of being able to detect residual vibration while printing, There is a demerit that the abnormality cannot be detected unless the ink is ejected, and a disadvantage that the ejection stability at that time is poor because the ink is ejected at the same time as the abnormality is detected.

As shown in FIG. 50, the resolution in the highest image quality mode is lower than that in the high speed image quality mode, and the resolution in the normal mode is lower than that in the high speed draft mode. The lower resolution has a merit that it is less susceptible to residual vibration because the ink droplets are larger.

The length of the inspection time corresponds to the length of the continuation time. The duration is the time during which the maximum voltage of the inspection waveform is continued. In other words, it is the time of a portion where the voltage value does not change in the inspection waveform. Note that the inspection waveform may adopt a voltage value lower than the intermediate potential, depending on the characteristics of the piezo element 200 and the inspection method.

<Fifth Embodiment>
Next, the printer 1 as a droplet discharge device that performs the maintenance operation of the inkjet head 100 based on the above-described detection result of the discharge abnormality will be described with reference to FIGS. 53 and 54. Hereinafter, description will be given based on these drawings, but the description will be centered on points that are different from the above-described embodiment, and description of similar matters will be omitted.

The printer 1 includes an inkjet head 100 as a droplet discharge unit, a support base 71 that supports a recording sheet P that is an example of a recording medium in the apparatus body 2, and a maintenance mechanism 72 that performs maintenance of the inkjet head 100. Equipped with. In addition, in the present embodiment, the configuration in which one inkjet head 100 is held by the carriage 32 is illustrated, but it is also possible to change to a configuration in which a plurality of inkjet heads 100 are held by the carriage 32.

The support base 71 is arranged near the center of the scanning area extending in the main scanning direction of the carriage 32 (horizontal direction in FIGS. 53 and 54), while the maintenance mechanism 72 is arranged at the end of the scanning area. There is. In the present embodiment, the side on which the maintenance mechanism 72 is arranged in the main scanning direction (right side in FIG. 53) may be referred to as “one digit side”, and the opposite side (left side in FIG. 53) may be referred to as “80 digit side”. is there. Further, the moving direction of the carriage 32 from the 1st digit side to the 80th digit side is defined as a first scanning direction +X, and the moving direction of the carriage 32 from the 80th digit side to the 1st digit side is defined as a second scanning direction −X.

The support base 71 may have a built-in heating element so as to function as a drying mechanism for promoting the drying of the recording paper P that has received the droplets. Further, as a drying mechanism for promoting the drying of the recording paper P, a heating element for heating the recording paper P from above the carriage 32, an air blower for blowing air toward the recording paper P, or the like may be provided.

The area in which the support base 71 is arranged is a recording area PA where droplets are ejected from the inkjet head 100 onto the recording paper P, while the area in which the maintenance mechanism 72 is arranged is recording on the recording paper P. It is a non-recording area NA in which (printing) is not performed. Then, the carriage 32, for example, moves forward in the first scanning direction +X at a substantially constant speed in the recording area PA, then decelerates in the non-recording area NA on the 80th digit side and changes direction at the end portion in the main scanning direction. Then, the direction-changed carriage 32 accelerates in the non-printing area NA on the 80th digit side, and then moves back in the second scanning direction -X at a substantially constant speed in the printing area PA again.

That is, the non-recording area NA is also an area for changing the direction of the reciprocating carriage 32, and the inkjet head 100 has a recording area PA in which the recording paper P is arranged and a recording area PA when the recording process is executed. It reciprocates to and from the non-recording area NA located outside. In the present embodiment, one scan (movement) of the carriage 32 in the first scanning direction +X or the second scanning direction −X is referred to as one pass, and the inkjet head 100 is used while the carriage 32 makes one pass on the recording paper P. A band-shaped area Ln (area shown by a chain double-dashed line in FIG. 53) in which recording can be performed is sometimes referred to as one line. Further, the direction change of the carriage 32 in the non-recording area NA may be referred to as return.

The recording paper P is placed on the support base 71 or retracted from the support base 71 by being transported by a transport mechanism (not shown) in the transport direction Y along the sub-scanning direction intersecting the main scanning direction. .. The recording paper P is conveyed by a predetermined distance (a distance corresponding to one line) in the conveyance direction Y while the carriage 32 changes direction in the non-recording area NA. That is, the printer 1 prints on the entire recording paper P by repeating recording for one line in the recording area PA and intermittent conveyance of the recording paper P.

As shown in FIG. 54, in the inkjet head 100, a plurality of nozzles 110 are arranged in the sub-scanning direction to form a nozzle row 110N, and a plurality of nozzle rows 110N are arranged in the main scanning direction. The plurality of nozzles 110 configuring the nozzle row 110N eject the same type of liquid (for example, ink of the same color), and the plurality of nozzle rows 110N include different types of liquid (for example, cyan, magenta, yellow, black, and the like). , Ink of different colors). It should be noted that the inkjet head 100 may be provided with a plurality of nozzle rows 110N arranged in a staggered manner, as shown in FIG. 5, corresponding to the same type of liquid.

The maintenance mechanism 72 arranged in the non-recording area NA on the one-digit side includes a wiping unit 81 arranged in order from a position closer to the recording area PA in the main scanning direction, and a flushing unit 74 having a liquid receiving portion 73. , And a cleaning mechanism 91.

The wiping unit 81 includes a wiping member (wiping member) 82 that can absorb liquid, a holding mechanism 83 that holds the wiping member 82, and a wiping motor 84. By forming the wiping member 82 from, for example, a non-woven fabric such as a synthetic resin, it is possible to realize a configuration in which the liquid is absorbed in the spaces between the fibers of the synthetic resin.

The wiping member 82 is detachably attached to the holding mechanism 83. Therefore, the wiping member 82 can be replaced with a new one after use. When the wiping member 82 is attached to the holding mechanism 83, a part thereof protrudes to the outside and functions as a wiping unit 85 capable of wiping the nozzle surface 36 where the nozzle 110 of the inkjet head 100 is open.

The holding mechanism 83 is supported by a pair of guide shafts 86 extending in the sub-scanning direction, and when the wiping motor 84 is driven, the holding mechanism 83 is moved in the sub-scanning direction by the driving force of the wiping motor 84. Then, the wiping unit 85 wipes the nozzle surface 36.

The cleaning mechanism 91 includes at least one suction cap 92, a plurality of moisturizing caps 93, a suction pump 94, and a capping motor 95. When the capping motor 95 is driven, the caps 92 and 93 relatively move in a direction approaching the inkjet head 100, and form a closed space in which the plurality of nozzles 110 forming the nozzle row 110N are opened.

The suction cap 92 forms a closed space in which a part of the plurality of nozzles 110 (for example, the nozzle 110 that ejects the same type of liquid) is opened. Then, when the suction pump 94 is driven with the suction cap 92 forming a closed space, the closed space becomes a negative pressure and ink is discharged from the nozzles 110 that open into the closed space (pump suction processing). ) Is executed. Suction cleaning is a kind of maintenance operation performed to eliminate the discharge abnormality of the nozzle 110, and is performed for each nozzle group surrounded by the suction cap 92.

The moisturizing cap 93 suppresses the drying of the nozzle 110 by forming a closed space in which the nozzle 110 opens. For example, the moisturizing cap 93 is provided for each nozzle row 110N, and the closed space is formed in a mode in which the plurality of nozzles 110 are divided for each nozzle row.

The inkjet head 100 moves to the standby position HP where the moisturizing cap 93 is arranged when recording is not performed or when the power is turned off. Then, the moisturizing cap 93 relatively moves in a direction approaching the inkjet head 100 to form a closed space in which the nozzle 110 opens. Enclosing the space where the nozzle 110 is opened by the cap 92 or the cap 93 is called capping. The inkjet head 100 is capped by the moisturizing cap 93 at the standby position HP when recording is not performed.

In addition, when the inkjet head 100 is arranged at a position corresponding to the liquid receiving portion 73 (for example, in the vertical direction above the liquid receiving portion 73), the inkjet head 100 ejects droplets toward the liquid receiving portion 73. I do.

In the present embodiment, the inkjet head 100 performs flushing for periodically ejecting droplets onto the liquid receiving portion 73 during the recording process on the recording paper P, thereby preventing or eliminating clogging of the nozzle 110. To do. In the following description, flushing that is regularly performed in the non-printing area NA between printing operations in the printing area PA is referred to as regular flushing in order to distinguish it from flushing that is performed as a recovery operation (maintenance operation) when the viscosity of the ink is increased.

Note that the regular flushing may be performed each time the liquid receiving portion 73 makes one reciprocating movement in the scanning region and is arranged at a position corresponding to the liquid receiving portion 73, or may be performed every time the liquid receiving portion 73 reciprocates a plurality of times. May be. Further, in one regular flushing, the droplets may be ejected from some of the nozzles 110, or the droplets may be ejected from all of the nozzles 110.

Next, the ejection abnormality detection process in the printer 1 of the present embodiment will be described.
In the present embodiment, the ejection abnormality detection unit 10 (see FIG. 16) as the ejection abnormality detection unit includes the vibration plate 121 (see FIG. 3) when droplets are ejected due to the regular flushing during the execution of the recording process. On the basis of the residual vibration waveform of, the ejection abnormality (ink droplet non-ejection) in the nozzle 110 is detected, and in the case of the ejection abnormality, the cause thereof is determined.

That is, the inkjet head 100 moves to the non-recording area NA between the ejection operations of the droplets on the recording paper P, and the inkjet head 100 moves to a position where the droplets ejected from the nozzles 110 can be received by the liquid receiving portion 73. When arranged, the discharge abnormality detection means 10 detects the situation of discharge abnormality in the nozzle 110.

The abnormal discharge may be detected each time the regular flushing is performed, or the regular flushing without the abnormal discharge may be performed. Further, the ejection abnormality may be detected for all of the nozzles 110 that ejected the droplets in the regular flushing, or the ejection abnormality may be detected for some of the nozzles 110 that ejected the droplets.

The regular flushing and the detection of the discharge abnormality may be performed by stopping the inkjet head 100 at a position corresponding to the liquid receiving portion 73, or the inkjet head 100 may move in the first scanning direction +X or the second scanning direction −X. You may go while. If the time Td (for example, 1 second) required for detecting the ejection abnormality is shorter than the time Tc (for example, 2 seconds) required for the carriage 32 to return, the inkjet head 100 does not stop in the non-recording area NA. Discharge abnormality can be detected.

When the ejection abnormality occurs in the nozzle 110 used for the recording process, dot omission may occur and the recording quality may deteriorate. Therefore, maintenance operations such as flushing, wiping, or suction cleaning may be performed to eliminate the ejection abnormality. It is desirable to do. For example, if the cause of the discharge abnormality is air bubbles, suction cleaning is performed, if the cause of the discharge abnormality is drying of the nozzle 110, flushing is performed, and the cause of the discharge abnormality is foreign matter such as paper dust near the outlet of the nozzle 110. If it is adhered, the ejection abnormality can be efficiently eliminated by performing wiping.

Here, during execution of the recording process on the recording paper P, recording for one line is performed, and return of the carriage 32 and regular flushing are performed until the recording for the next one line is performed. Then, the droplet discharge operation, which is a part of the recording process, is temporarily stopped. Then, the droplets that have landed on the recording paper P wet and spread on the surface of the recording paper P as time elapses or dry, so if there are variations in the time during which the recording process is interrupted, they will be adjacent in the sub-scanning direction. The recording quality may be deteriorated because the recording result may not be uniform due to the color change between the line and the line.

In the present embodiment, the threshold value of the recording interruption time at which the recording quality deteriorates is Tng. Further, the times required for flushing, wiping, and suction cleaning are Tf, Tw, and Tv, respectively. The time Tf required for flushing is the time when the inkjet head 100 is stopped at a position corresponding to the liquid receiving portion 73. Further, the time Tv required for suction cleaning is the time required for performing one suction cleaning performed on the nozzle 110 surrounded by the suction cap 92.

The threshold value Tng of the recording interruption time at which the recording quality deteriorates depends on the components of the recording paper P and the liquid to be ejected, the presence or absence of a drying mechanism, the environmental conditions such as temperature and humidity, and is generally Tf≦Tw≦Tng<Tv. The relationship is established. That is, if the suction processing is executed by interrupting the recording process for one recording sheet P, there is a high possibility that the recording result will be different before and after the interruption and the recording quality will be deteriorated. On the other hand, even if the recording operation on one recording sheet P is interrupted and flushing or wiping is executed, the difference in the recording results before and after the interruption is small, and the recording quality is not likely to deteriorate so much.

Therefore, in the present embodiment, when the ejection abnormality detection unit 10 detects that there is an ejection abnormality nozzle 110, if the time required for the maintenance operation for eliminating the ejection abnormality of the nozzle 110 is the threshold value Tng or less, recording is performed. The processing is interrupted to perform the maintenance operation. If the time required for the maintenance operation is longer than the threshold value Tng, the maintenance operation is suspended and the recording processing is continued.

For example, when the cause of the discharge abnormality of the nozzle 110 is the inclusion of air bubbles, it is preferable to perform suction cleaning as a maintenance operation, but the time Tv required for performing suction cleaning is longer than the threshold value Tng. Therefore, when the nozzle 110 in which the ejection abnormality has occurred due to the inclusion of air bubbles is detected, the suction cleaning is suspended, and the suction cleaning is executed after the recording process on the recording paper P is completed. That is, if the recording process on the recording sheet P is interrupted and suction cleaning is performed, there is a high possibility that the difference in the recording results before and after the interruption becomes large. Then, if the recording result changes and the recording quality deteriorates during recording on one recording sheet P, the recording sheet P must be discarded. Therefore, in order to suppress wasteful consumption of the recording paper P due to interruption of the recording process, the recording process is continued without performing suction cleaning.

Even if there is a nozzle 110 that has an ejection abnormality, if it is a nozzle 110 that does not eject droplets onto the recording paper P, or the positions of the ejection abnormality nozzles 110 are individually dispersed. In many cases, even if the recording process is continued without performing the maintenance operation, the recording quality often does not deteriorate so much.

However, when the maintenance operation is suspended and the recording process is continued in this way, the liquid to be ejected from the ejection abnormality nozzle 110 based on the state of the ejection abnormality nozzle 110 detected by the ejection abnormality detection unit 10. It is preferable to perform complementary printing (interpolation printing) for compensating the droplets with the droplets discharged from the nozzles 110 in which the discharge abnormality has not occurred.

For example, when an ejection abnormality occurs in one of the plurality of nozzles 110 ejecting the same type (color) of liquid (ink), the normal nozzle 110 near the ejection abnormality nozzle 110 The dot dropout is complemented by ejecting a droplet larger than the droplet to be ejected from the ejection abnormality nozzle 110. Alternatively, when an ejection abnormality occurs in the nozzle 110 that ejects the black ink, the droplets of yellow, cyan, and magenta are overlapped at the positions where the droplets that should be ejected from the nozzle 110 land, and thereby the black ink is ejected. Complement the missing ink.

On the other hand, when the nozzle 110 in which the discharge abnormality occurs due to the drying is detected by the detection of the discharge abnormality associated with the regular flushing, the flushing is performed as the maintenance operation before the recording process of the next line is performed. To do. That is, since the time Tf required to perform the flushing operation is equal to or less than the threshold value Tng, even if the recording process is interrupted and the maintenance is performed, the difference in the recording result is not so large before and after the interruption, so that the ejection abnormality is resolved. It is preferable to restart the recording process after that.

In addition, when the nozzle 110 in which the discharge abnormality occurs due to the adhesion of the foreign matter is detected by the detection of the discharge abnormality associated with the regular flushing, the wiping is performed as the maintenance operation before the recording process of the next line is performed. .. That is, since the time Tw required to perform the wiping operation is equal to or less than the threshold value Tng, even if the recording process is interrupted and the maintenance is performed, there is not much difference in the recording result before and after the interruption, so that the ejection abnormality is resolved. It is preferable to restart the recording process after that.

Next, the operation of the printer 1 of this embodiment will be described.
When the ejection abnormality detection unit 10 detects the ejection abnormality nozzle 110, the printer 1 according to the present exemplary embodiment performs the maintenance operation when the time required for the maintenance operation for eliminating the ejection abnormality is longer than the threshold value Tng. Hold and continue the recording process. Therefore, the recording paper P is not wasted by stopping the recording process. Then, even if the recording process is continued in the state where the nozzle 110 having the ejection abnormality is present, it is possible to suppress the deterioration of the recording quality by performing the above-mentioned complementary printing, for example.

Further, when the time required for the maintenance operation is equal to or less than the threshold value Tng, the recording processing is restarted after the maintenance operation is executed, so that the recording processing can be completed while suppressing the deterioration of the recording quality.

Note that flushing and wiping are examples of the maintenance operation in which the time required to eliminate the ejection abnormality is the threshold Tng or less. Since the flushing unit 74 for performing flushing and the wiping unit 81 for performing wiping are in the non-recording area NA for performing regular flushing, after the ejection abnormality is detected and before the recording of the next line is performed. The maintenance operation can be executed promptly.

For example, when the ejection abnormality associated with the regular flushing is detected during the backward movement in the second scanning direction −X in the non-recording area NA, and the ejection abnormal nozzle 110 is detected by this detection, the end portion on the one-digit side is detected. Flushing can be performed in the course of the outward movement in the first scanning direction +X after the direction is changed by.

Further, since the wiping unit 81 is located between the recording area PA and the liquid receiving portion 73 in the main scanning direction, it is possible to detect an ejection abnormality due to regular flushing during the backward movement in the second scanning direction -X in the non-recording area NA. Then, the wiping unit 85 can perform the wiping in the middle of the outward movement in the first scanning direction +X after the direction change at the end on the one-digit side.

When a plurality of abnormal discharge nozzles 110 are detected by one detection operation, and the abnormal discharge nozzles 110 include those caused by different causes, a maintenance operation whose execution time is equal to or less than the threshold Tng is executed, and then the detection operation is performed again. May be performed.

For example, when the ejection abnormality nozzle 110 caused by adhesion of foreign matter and the ejection abnormality nozzle 110 caused by drying are detected during the backward movement in the second scanning direction −X, flushing is performed at the position corresponding to the liquid receiving portion 73 as it is. After that, the nozzle 110 in which the ejection abnormality is detected is detected again. Then, when the ejection abnormality nozzle 110 due to the adhesion of the foreign matter is detected by the re-detection, the wiping is performed at the time of the outward movement in the first scanning direction +X after the direction is changed at the end on the one-digit side. As described above, if the threshold value Tng is not exceeded, it is possible to continuously execute a plurality of maintenance operations.

As an example, it is assumed that the times required for flushing, wiping, and suction cleaning are 3 seconds, 5 seconds, and 60 seconds, the threshold value Tng of the recording interruption time is 20 seconds, and the time Td required for detection is 1 second. In this case, the first detection (1 second), the flushing (3 seconds), the second detection (1 second), and the wiping (5 seconds) are executed within a range not exceeding the threshold Tng of 20 seconds. It is possible. Furthermore, if the ejection abnormality nozzle 110 is detected by the third detection after the wiping and the third detection, the maintenance operation for eliminating the ejection abnormality is suspended and the recording process is continued. Alternatively, the maintenance operation may be repeated within a range not exceeding the threshold value Tng.

Alternatively, when the ejection abnormality nozzle 110 due to the inclusion of bubbles and the ejection abnormality nozzle 110 due to drying are detected by one detection operation, the maintenance operation is suspended and the recording process is continued, and after the recording process is completed, the maintenance is performed. The operation may be executed.

When detecting abnormal discharge during regular flushing, use a waveform for inspection that involves the ejection of droplets that accompanies the ejection of droplets, and do not have a vibration suppression waveform after that. Preferably. With this configuration, the residual vibration of the pressure chamber 141 (vibration plate 121) can be detected more reliably.

Such ejection abnormality can also be detected based on the residual vibration of the pressure chamber 141 when a droplet is ejected onto the recording paper P. In this case, although the wasteful consumption of the liquid for the detection is suppressed, there is a possibility that the ejection abnormality in the nozzle 110 which is not used for recording cannot be detected, or the residual vibration sufficient for the detection cannot be obtained. There is. In that respect, if the ejection abnormality is detected based on the residual vibration of the pressure chamber 141 when the liquid droplets are ejected in accordance with the regular flushing, the liquid is not wastefully consumed only for the purpose of detection and is also used for the detection. This is preferable because the detection accuracy can be improved by using a suitable drive waveform.

According to the fifth embodiment, the following effects can be obtained.
(1) When the ejection abnormality detection unit 10 detects that there is an ejection abnormality nozzle 110, the time required for this maintenance operation is suppressed to the threshold value Tng or less even if the recording operation is interrupted and the maintenance operation is performed. .. Therefore, even if the recording process is interrupted, the threshold value Tng is set so that the change of the ejection result on the recording paper P is allowed before and after the interruption, so that the recording operation is restarted after the maintenance operation. The recording process can be completed. Accordingly, the ejection operation is not stopped for the maintenance operation, and the recording paper P is not wasted. On the other hand, if the time required for the maintenance operation is longer than the threshold value Tng, the maintenance operation is suspended and the recording process on the recording paper P is continued, so that the deterioration of the recording quality due to the interruption of the ejection operation can be suppressed. Therefore, when the ejection abnormality of the nozzle 110 is detected, it is possible to suppress the wasteful consumption of the recording paper P due to the suspension or interruption of the recording process.

(2) By performing the suspended maintenance operation after the recording process is completed, it is possible to eliminate the ejection abnormality of the nozzle 110 before executing the recording process on the next recording sheet P.

(3) By supplementing the droplets to be ejected from the nozzle 110 with abnormal ejection with the droplets ejected from the nozzle 110 with no abnormal ejection, the recording process is continued in the presence of the nozzle 110 with abnormal ejection. Also, it is possible to suppress deterioration of recording quality.

(4) Since it is possible to detect the status of the discharge abnormality in the nozzle 110 based on the vibration waveform of the pressure chamber 141 vibrated by the driving of the actuator 120 without separately providing a sensor or the like for detecting the discharge abnormality, the apparatus The configuration of can be simplified.

(5) Even when a droplet is ejected from the nozzle 110 when the ejection abnormality of the nozzle 110 is detected, the ejected droplet can be received by the liquid receiving portion 73. Therefore, it is possible to suppress the contamination of the recording paper P and the inside of the apparatus due to the liquid droplets ejected from the nozzles 110 when the ejection abnormality is detected.

(6) The ejection mechanism of the nozzle 110 can be eliminated by the cleaning mechanism 91 performing cleaning so that the liquid flows out from the nozzle 110. However, since the time required for cleaning is longer than the threshold value Tng, if the recording process is interrupted and cleaning is performed, the recording quality may deteriorate. In that respect, according to the above-described embodiment, when the ejection abnormality detection unit 10 detects that there is an ejection abnormality nozzle 110, the cleaning is suspended and the recording processing is continued, so that the recording quality is interrupted by the interruption of the recording processing. The decrease can be suppressed.

<Sixth Embodiment>
Next, the printer 1 as an example of the droplet discharge device including the filter will be described with reference to FIGS. 55 to 57. Hereinafter, description will be given based on these drawings, but the description will be centered on points that are different from the above-described embodiment, and description of similar matters will be omitted.

As shown in FIG. 55, the printer 1 can supply a head unit 35 as an example of a droplet discharge unit and a liquid (for example, ink) contained in an ink cartridge 31 as an example of a liquid supply source to the head unit 35. And at least one supply mechanism 261. That is, the supply mechanism 261 supplies the liquid from the ink cartridge 31 to the head unit 35 via the liquid supply passage 262. The head unit 35 has a plurality of nozzles 110 for ejecting the liquid supplied by the supply mechanism 261 as droplets, and the droplets are ejected from the nozzles 110 to the recording paper P (see FIG. 1) as an example of the medium. The recording process is performed by discharging.

The ink cartridge 31 of the present embodiment is not mounted on the carriage 32 and is arranged at a place different from the carriage 32. Even when a plurality of supply mechanisms 261 are provided, the configuration of each supply mechanism 261 is the same, so in FIG. 55, one supply mechanism 261 is shown and the description of the other supply mechanisms is omitted.

Further, as shown in FIG. 3, the head unit 35 includes an electrostatic actuator 120 as an example of an actuator that vibrates a cavity 141 as an example of a pressure chamber communicating with the nozzle 110. That is, the head unit 35 drives the electrostatic actuator 120 to vibrate the cavity 141 to eject the liquid droplets from the nozzle 110. The control unit 6 (see FIG. 2) functions as an example of an ejection state detection unit that can detect the state of the cavity by detecting the vibration waveform of the cavity 141 that is vibrated by driving the electrostatic actuator 120. Further, the electrostatic actuator 120 performs a flushing operation as an example of a maintenance operation of the head unit 35 that discharges the liquid whose viscosity is increased by ejecting a droplet from the nozzle 110, and also functions as an example of a maintenance unit.

As shown in FIG. 55, the printer 1 includes a suction cap 92 and a suction pump 94. The cap 92 contacts the head unit 35 and closes the space 263 exposed by the nozzle 110. Hereinafter, the space 263 that is closed by the cap 92 coming into contact with the head unit 35 is also referred to as a sealed space 263. Further, the suction pump 94 performs suction cleaning for discharging the liquid from the nozzle 110 by applying a negative pressure to the closed space 263. The cap 92 is provided with an atmosphere release valve 264 that connects or does not connect the closed space 263 and the atmosphere.

The ink cartridge 31 is a storage container that can store a liquid, and is detachably held by the mounting portion 266. The liquid supply source may be a storage tank fixed to the mounting portion 266 instead of the ink cartridge 31. Further, the mounting portion 266 can hold a plurality of ink cartridges 31 and storage tanks in which the type and color of the liquid to be stored are different.

The supply mechanism 261 includes a liquid supply passage 262 that supplies liquid from the ink cartridge 31 on the upstream side to the nozzle 110 on the downstream side. The liquid supply path 262 is provided with a supply pump 267 that causes the liquid to flow in the supply direction A from the ink cartridge 31 toward the nozzle 110, a filter unit 268, and a pressure adjustment valve 269 that adjusts the pressure of the liquid. There is. The supply pump 267 can be, for example, a gear pump or a diaphragm pump.

The filter unit 268, the pressure adjusting valve 269, and the head unit 35 are provided with the first filter 271 to the third filter 273 as an example of a functional unit. These filters 271 to 273 are expendable supplies that collect bubbles and foreign matter in the passing liquid, and the ability to pass the liquid decreases as the bubbles and foreign matter are collected.

That is, the filter unit 268 includes the first filter 271 and is partitioned by the first filter 271 into the upstream chamber 275 and the downstream chamber 276. The filter unit 268 is detachably attached to the liquid supply passage 262. The pressure adjusting valve 269 is provided with the second filter 272, and the head unit 35 is provided with the third filter 273. The pressure adjusting valve 269 and the head unit 35 are provided so as to be attachable to and detachable from the liquid supply passage 262. That is, the filters 271 to 273 are arranged so as to be attachable to and detachable from the liquid supply passage 262 together with the filter unit 268, the pressure adjusting valve 269, and the head unit 35, respectively.

The pressure adjusting valve 269 includes a filter chamber 278 and a supply chamber 279 that are partitioned by the second filter 272. Further, the pressure adjusting valve 269 includes a pressure adjusting chamber 281, which communicates with the supply chamber 279 through the communication hole 280, a valve body 282 provided between the pressure adjusting chamber 281 and the supply chamber 279, and a valve body 282. And a biasing member 283 that biases in the valve closing direction. That is, the valve body 282 is inserted into the communication hole 280, and the valve body 282 biased by the biasing member 283 is provided so as to close the communication hole 280.

Further, in the pressure adjusting chamber 281, a part of the wall surface is constituted by a diaphragm 284 which is bendable and deformable along the urging direction of the urging member 283. The diaphragm 284 receives the atmospheric pressure on the outer surface side (the left surface side in FIG. 55) while receiving the liquid pressure in the pressure adjusting chamber 281 on the inner surface side (the right surface side in FIG. 55). Therefore, the diaphragm 284 is flexibly displaced according to the change in the pressure difference between the pressure inside the pressure adjustment chamber 281 and the pressure received on the outer surface side, and the valve body 282 is displaced along with the displacement of the diaphragm 284, so that the valve is opened.

The liquid supply path 262 has a plurality of (four in the present embodiment) first to fourth connection channels 286 to 289. Specifically, the first connection flow path 286 connects the ink cartridge 31 and the supply pump 267, and the second connection flow path 287 connects the supply pump 267 and the upstream chamber 275 of the filter unit 268. The third connection flow path 288 connects the downstream chamber 276 of the filter unit 268 and the filter chamber 278 of the pressure adjustment valve 269, and the fourth connection flow path 289 is the pressure adjustment chamber 281 of the pressure adjustment valve 269 and the head unit 35. And the reservoir 143 of.

The liquid supply passage 262 is a passage located between the ink cartridge 31 and the nozzle 110. That is, the liquid supply passage 262 includes the first connection passage 286 to the fourth connection passage 289, the filter unit 268, the pressure adjusting valve 269, and the head unit 35, and the liquid supply passage 262 includes the first filter 271 to the third filter 271. A filter 273 is arranged.

Then, the control unit 6 (see FIG. 1) of the present embodiment stores the passing amount, which is the amount of the liquid that has passed through the filters 271 to 273. That is, the control unit 6 counts the number of times droplets are ejected from the nozzle 110 and the number of times maintenance of the head unit 35 is performed. Then, the amount of the liquid supplied from the ink cartridge 31 to the nozzle 110 and consumed is calculated based on these numbers of times and stored as the passing amount.

Next, in the printer 1 configured as described above, a process of detecting clogging of the filters 271 to 273 will be described. The filter clogging detection process is performed periodically or based on an instruction from the user.

As shown in FIG. 56, the control unit 6 determines in step S1001 whether the calculated passage amount is larger than a threshold amount stored in advance. That is, the foreign matter is mixed in from the outside or is precipitated from the liquid, but when the liquid passes through the filters 271 to 273, it is collected by the filters 271 to 273. Therefore, when the passing amount is less than or equal to the threshold amount (step S1001: NO), the possibility of clogging of the filters 271 to 273 is low, and the control unit 6 ends the clogging detection process. The threshold amount is a value that is set in advance based on experiments, and is determined according to the collection ability of the filters 271 to 273, the area of the filters 271 to 273, the ease of mixing and depositing foreign matters, and the like. It is a value.

On the other hand, when the passing amount is larger than the threshold amount (step S1001: YES), the control unit 6 proceeds to step S1002 and performs suction cleaning. That is, the control unit 6 closes the atmosphere opening valve 264 while the head unit 35 is capped with the cap 92, and further drives the suction pump 94. When the suction cleaning is completed, the controller 6 separates the cap 92 from the head unit 35. Subsequently, the control unit 6 executes the ejection inspection process shown in FIG. 57 in step S1003.

As shown in FIG. 57, in the ejection inspection process, the control unit 6 performs the residual vibration detection process, the detection waveform measurement, and the ejection abnormality determination process as in steps S104 to S106 (see FIG. 24) in the first embodiment. (Steps S1101 to S1103) are sequentially executed.

Next, returning to FIG. 56, in step S1004, the control unit 6 executes a flushing operation of ejecting droplets from the nozzle 110. That is, the control unit 6 first inputs a signal to the carriage motor driver 43 to move the carriage 32, and stops the carriage 32 at a position where the nozzle 110 and the liquid receiving unit 73 face each other. Further, the control unit 6 inputs a signal to the head driver 33 to continuously eject the droplets of the maximum diameter from all the nozzles 110 that eject the droplets of the color (type) to be inspected.

Therefore, the liquid flows through the liquid supply path 262 at the maximum flow rate and is supplied to the inkjet head 100. In other words, the head unit 35 ejects liquid from the nozzle 110 so that the ejection amount per unit time ejected from the nozzle 110 in accordance with the flushing operation becomes the same as the maximum amount ejected from the nozzle 110 per unit time during the recording process. Is discharged.

Subsequently, in step S1005, the control unit 6 executes the ejection inspection process as in step S1003. Then, in step S1006, the control unit 6 compares the inspection results of step S1003 and step S1005 and determines whether or not air bubbles are mixed in the nozzle 110 or the cavity 141. That is, when the bubbles in the nozzle 110 and the cavity 141 have not increased before and after the flushing operation (step S1006: NO), the control unit 6 determines that the filters 271 to 273 are functioning normally. And ends the clogging detection process.

On the other hand, when the number of the cavities 141 in which the bubbles are mixed in the inspection of step S1006 is increased as compared with the number of the cavities 141 in which the bubbles are mixed in the inspection of step S1003 (step S1006). : YES), and moves the process to step S1007. Then, in step S1007, the control unit 6 notifies the necessity of replacement of the filters 271 to 273. That is, the control unit 6 prompts the replacement of the filters 271-273 by displaying a message on the operation panel 7 as an example of the notification unit, and ends the clogging detection process.

Next, the operation of detecting clogging of the filters 271 to 273 will be described.
As shown in FIG. 55, when suction cleaning is performed in the printer 1, bubbles and foreign matter are discharged together with the liquid from the nozzle 110 covered with the cap 92. Therefore, when the control unit 6 performs the ejection inspection process after the suction cleaning, it is possible to reduce the risk that the nozzle 110 or the cavity 141 in which bubbles are mixed is detected.

When the printer 1 performs a flushing operation of ejecting liquid droplets from the nozzle 110 subsequent to the ejection detection process, the liquid is supplied from the ink cartridge 31 to the nozzle 110 via the liquid supply passage 262. By the way, the liquid supply path 262 is provided with filters 271 to 273, and the liquid is supplied to the nozzle 110 through these filters 271 to 273. Therefore, if the filters 271 to 273 are clogged, the flow of the liquid is further hindered, and the amount of liquid passing through the filters 271 to 273 per unit time exceeds the amount of liquid that the nozzle 110 can discharge per unit time. The amount of liquid that can be supplied to the nozzle 110 may decrease.

In other words, when the filters 271 to 273 are clogged, a sufficient amount of liquid may not be supplied even if droplets are ejected from the nozzle 110. Then, the negative pressure in the liquid supply path 262 between the nozzle 110 and the filters 271-273 increases, and the risk of drawing air from the nozzle 110 increases. Then, by performing the discharge inspection process, it is possible to detect the nozzle 110 and the cavity in which bubbles are mixed. That is, the control unit 6 detects the vibration waveform of the cavity 141 before and after the flushing operation, and determines whether the filters 271 to 273 are clogged based on the change in the state of the cavity 141 due to the flushing operation.

Then, when the change in the state inside the cavity 141 detected before and after the flushing operation is an increase in bubbles inside the cavity 141, the control unit 6 determines that the filters 271 to 273 are clogged. Specifically, when the number of cavities 141 in which air bubbles are detected in the ejection inspection process after the flushing operation is larger than before the flushing operation, it is presumed that the air bubbles were mixed in with the flushing operation. That is, it is considered that the supply mechanism 261 is in a state in which the filters 271 to 273 are clogged and cannot supply a sufficient amount of liquid. Therefore, when it is determined that the filters 271 to 273 are clogged and malfunctions, the control unit 6 prompts the operation panel 7 to replace the filters 271 to 273.

According to the sixth embodiment, the following effects can be obtained in addition to the effects (1) to (6) of the fifth embodiment.
(7) Some printers 1 include the control unit 6 that detects the state inside the cavity 141 by driving the electrostatic actuator 120 to vibrate the cavity 141 and detect the vibration waveform of the cavity 141. .. For example, the vibration waveform of the cavity 141 changes depending on whether the cavity 141 or the nozzle 110 is filled with a liquid or when the air bubbles are mixed in the cavity 141 or the nozzle 110. Therefore, it is determined based on the detected vibration waveform whether the droplet can be normally ejected from the nozzle 110. In addition, the vibration waveform of the cavity 141 is detected before the flushing operation, and the vibration waveform of the cavity 141 is detected after the flushing operation. Then, by comparing the detected vibration waveforms, the change in the state inside the cavity 141 can be known. That is, when the change in the state inside the cavity 141 and the change predicted from the flushing operation are different, the malfunction of the filters 271 to 273 can be determined. Therefore, it is possible to detect the malfunction of the filters 271 to 273 while suppressing an increase in the number of parts by using the control unit 6 that originally detects the state inside the cavity 141 for discharging droplets. it can.

(8) If the change in the state inside the cavity 141 is an increase in bubbles, it can be inferred that the bubbles were mixed from the nozzle 110 in accordance with the flushing operation. Therefore, it is possible to determine that the filters 271-273 through which the liquid supplied as the liquid is consumed by the flushing operation pass are malfunctioning.

(9) When the filters 271 to 273 are clogged, the flow rate, which is the amount of liquid that can pass per unit time, decreases. Therefore, when the flow rate that can pass through the filters 271 to 273 becomes smaller than the amount discharged from the nozzle 110 per unit time, air may enter from the nozzle 110. In this respect, it is possible to judge the malfunction of the filters 271-273 for collecting the foreign matter based on the change in the state inside the cavity 141 before and after the droplets are ejected from the nozzle 110.

(10) Since the ejection amount ejected from the nozzle 110 by the electrostatic actuator 120 is the same as the maximum amount ejected from the nozzle 110 during the recording process, it is possible to easily determine the malfunction of the filters 271 to 273.

(11) Droplets can be ejected from the nozzle 110 by the electrostatic actuator 120 that vibrates the cavity 141 to detect the state inside the cavity 141. Therefore, the number of parts can be further reduced as compared with the case where each mechanism is provided separately.

(12) Since the operation panel 7 prompts replacement, the filter unit 268 including the malfunctioning filters 271 to 273, the pressure adjustment valve 269, and the head unit 35 can be replaced at appropriate timing.

<Seventh Embodiment>
Next, the printer 1 as an example of the droplet discharge device including the moisturizing cap 93 will be described with reference to FIGS. 58 to 66. Hereinafter, description will be given based on these drawings, but the description will be centered on points that are different from the above-described embodiment, and description of similar matters will be omitted.

As shown in FIG. 58, a moisturizing mechanism 361 as an example of a maintenance unit includes a cap holder 362 and a moisturizing cap 363 held by the cap holder 362. The moisturizing cap 363 is a cap 93 as an example of a cap part that is in contact with the head unit 35 as an example of a droplet discharge part and closes the space 263 (see FIG. 61) facing the nozzle 110, and at least one cap 93. And a supporting portion 365 for supporting the.

The moisturizing caps 93 are spaced from each other in the scanning direction of the carriage 32 so as to correspond to the nozzle rows 110N (not shown in FIG. 58) of the head unit 35, and the same number as the nozzle rows 110N (the present embodiment). Then 5) are arranged. Each cap 93 includes a frame portion 367 made of an elastic member such as an elastomer and having a substantially rectangular shape in a plan view, and a rigid member 368 fitted to the frame portion 367.

As shown in FIGS. 59 and 60, the rigid member 368 is made of a hard synthetic resin having a high gas barrier property such as PP (polypropylene). As the material of the rigid member 368, any material can be adopted as long as it is a hard material having a high gas barrier property, and for example, PE (polyethylene), PET (Polyethylene terephthalate) or the like may be adopted. ..

The rigid member 368 includes a main body 370 having a substantially rectangular parallelepiped shape, and a protruding portion 371 protruding from the main body 370 and having a circular tubular shape. That is, the protrusion 371 has the hollow portion 372 inside.

In the following description, the surface of the main body portion 370 on which the protruding portion 371 is formed is the lower surface, and the surface opposite to the lower surface is the upper surface 370a. That is, the upper surface 370a is a surface that forms the inner bottom surface of the cap 93 when the rigid member 368 is fitted to the frame portion 367. The directions of the main body 370 that intersect the vertical direction are the longitudinal direction and the lateral direction, respectively. Further, among the side surfaces of the main body portion 370, one of both side surfaces in the lateral direction is a first side surface 370b and the other is a second side surface 370c.

On the upper surface 370a of the main body 370, a recess 374 is formed at the center position in the longitudinal direction in the lateral direction. On the inner bottom surface of the concave portion 374, a convex strip 375 extending in the lateral direction and a cap portion 376 having a substantially rectangular plate shape in plan view are integrally formed with the main body portion 370. An annular recess 377 is formed at the boundary between the ridge 375 and the cap 376.

Step portions 378 are formed on both side surfaces of the cap portion 376 in the lateral direction. It should be noted that both ends in the longitudinal direction of each step portion 378 are inclined so as to bend downward at a right angle and then spread obliquely downward.

As shown in FIG. 59, the main body portion 370 is formed with a through hole 380 penetrating from the first side surface 370b in the lateral direction. Further, a first groove 381 connecting the through hole 380 and the annular recess 377 is formed on the first side surface 370b in a meandering manner.

That is, the first groove portion 381 is composed of a first longitudinal groove portion 381a to a third longitudinal groove portion 381c extending in the longitudinal direction and a first vertical groove portion 381d to a third vertical groove portion 381f extending in the vertical direction. The first longitudinal groove portion 381a to the third longitudinal groove portion 381c are formed at different positions in the vertical direction, and the first vertical groove portion 381d to the third vertical groove portion 381f are formed at different positions in the longitudinal direction and the vertical direction. Has been done.

Specifically, the first longitudinal groove portion 381a connects the through hole 380 and the lower ends of the first upper and lower groove portions 381d. The second longitudinal groove portion 381b connects the upper end of the first vertical groove portion 381d and the lower end of the second vertical groove portion 381e, and the third longitudinal groove portion 381c connects the upper end of the second vertical groove portion 381e and the third vertical groove portion 381f. Connect to the bottom. Further, the upper ends of the third upper and lower groove portions 381f face the lower surface of the cap portion 376.

As shown in FIG. 60, the second side surface 370c is formed with a second groove portion 382 having one end connected to the through hole 380, and a connection for connecting the other end of the second groove portion 382 and the hollow portion 372. A hole 383 is formed. That is, the second groove portion 382 is formed to meander so as to connect the through hole 380 and the connection hole 383.

The second groove portion 382 is composed of a fourth longitudinal groove portion 382a and a fifth longitudinal groove portion 382b extending in the longitudinal direction, and a fourth vertical groove portion 382c to a sixth vertical groove portion 382e extending in the vertical direction. The fourth longitudinal groove portion 382a and the fifth longitudinal groove portion 382b are formed at different positions in the vertical direction, and the fourth vertical groove portion 382c to the sixth vertical groove portion 382e are formed at different positions in the longitudinal direction. ..

Specifically, the lower ends of the fourth upper and lower groove portions 382c are connected to the through holes 380. The fourth longitudinal groove portion 382a connects the upper ends of the fourth vertical groove portion 382c and the upper end of the fifth vertical groove portion 382d, and the fifth longitudinal groove portion 382b connects the lower end of the fifth vertical groove portion 382d and the sixth vertical groove portion 382e. Is connected to the upper end of. The lower ends of the sixth upper and lower groove portions 382e are connected to the connection holes 383.

As shown in FIG. 61, when the rigid member 368 is attached to the frame portion 367, the first side surface 370b and the second side surface 370c of the rigid member 368 come into close contact with the inner surface of the frame portion 367. Therefore, the openings of the first groove portion 381, the second groove portion 382, the through hole 380, and the connection hole 383 are covered by the inner surface of the frame portion 367, and each serves as a ventilation path, and the gap between the main body portion 370 and the cap portion 376 is also formed. It becomes an air passage. Therefore, the air passage and the hollow portion 372 form an atmosphere communication portion 384 that communicates the closed space 263 facing the nozzle 110 with the atmosphere. The closed space 263 is a space that the nozzle 110 faces and is closed by the cap 93 coming into contact with the head unit 35. Then, the moisturizing mechanism 361 performs the capping operation as an example of the maintenance operation of the head unit 35 by the cap 93 contacting the head unit 35 and closing the space 263 facing the nozzle 110. Further, for example, when the liquid adheres to the atmosphere communicating portion 384 and dries, the moisture retaining cap 363 loses its function of closing the enclosed space 263 in a state where the enclosed space 263 facing the nozzle 110 communicates with the atmosphere. It is a product.

As shown in FIG. 62, the moisturizing mechanism 361 includes a cam mechanism 386 capable of bringing the cap 93 into contact with or away from the head unit 35 by moving the cap holder 362 up and down. That is, the moisturizing cap 363 and the cap holder 362 are configured to be integrally movable up and down by the cam mechanism 386. In addition, the moisturizing mechanism 361 includes a restricting portion 387 that contacts the raised cap holder 362 and restricts movement thereof.

The cam mechanism 386 includes a rotating shaft 388 that is rotated by rotational driving of the capping motor 95 (see FIG. 54), and a substantially triangular cam frame 389 having a base end fixed to the rotating shaft 388. A shaft portion 391 of the cam roller 390 is rotatably supported at the tip of the cam frame 389. The shaft portion 391 of the cam roller 390 is configured to penetrate the cam frame 389 and project from both side surfaces of the cam frame 389. Therefore, when the cam frame 389 rotates about the rotation shaft 388 as the rotation shaft 388 rotates, the cam roller 390 rotatably supported by the tip of the cam frame 389 orbits about the rotation shaft 388.

Further, in the cap holder 362, a cam groove 393 is formed at a position corresponding to the cam mechanism 386. The cam groove 393 has an opening 394 that opens downward, and the cam mechanism 386 supports the cap holder 362 by inserting the cam mechanism 386 from the opening 394.

More specifically, the cam groove 393 of the cap holder 362 is formed with a flat surface portion 395 located above the opening portion 394 and a first inclined surface portion 396 continuous from the flat surface portion 395. Further, a concave surface portion 397 and a second inclined surface portion 398 continuous from the concave surface portion 397 are formed at positions where the cam groove 393 can contact both ends of the shaft portion 391. Note that the first sloped portion 396 and the second sloped portion 398 are formed so as to be substantially parallel to each other.

Next, the operation of moving the moisturizing cap 363 relative to the head unit 35 will be described. The head unit 35 is assumed to be located above the moisturizing cap 363.

As shown in FIG. 62, when the cap holder 362 is attached to the cam mechanism 386, the cap holder 362 is supported by the peripheral surface of the base end portion of the cam frame 389. Further, the shaft portion 391 of the cam roller 390 is arranged in the concave surface portion 397. That is, since the shaft portion 391 locks the concave surface portion 397, the removal operation of the cap holder 362 from the cam mechanism 386 is restricted even when the cap holder 362 is lifted up or moved left and right, for example. ..

As shown in FIG. 63, when the rotation shaft 388 rotates in the forward direction (counterclockwise direction in FIG. 63 ), the shaft portion 391 of the cam roller 390 makes an orbital movement around the rotation shaft 388 and separates from the concave surface portion 397. To do. Further, the cam roller 390 rolls along the first slope portion 396 of the cam groove 393. Therefore, the cap holder 362 and the moisturizing cap 363 are pushed up while being guided by the guide portion (not shown) and move toward the head unit 35.

As shown in FIG. 64, when the rotating shaft 388 further rotates in the positive direction, the cam roller 390 moves from the first slope portion 396 to the flat surface portion 395 and further pushes the cap holder 362 up. Then, each cap 93 that moves together with the cap holder 362 contacts the head unit 35, and surrounds the corresponding nozzle 110 to close the space 263 facing each nozzle 110. In this state, the regulation portion 387 regulates the rise of the cap holder 362, and the cam roller 390 and the shaft portion 391 are located above the opening portion 394.

Therefore, as shown in FIG. 65, when the rotary shaft 388 is rotated in a state in which the head unit 35 is located at a position different from the position above the moisturizing cap 363, the cap holder 362 does not move with respect to the cam mechanism 386. Can be removed. Specifically, by rotating the rotary shaft 388 in the forward direction so that the cam roller 390 supports the flat surface portion 395 and displacing the regulating portion 387, the cap holder 362 and the moisturizing cap 363 are removed and replaced. You can

Next, a process of detecting malfunction of the moisturizing cap 363 in the printer 1 configured as above will be described. The malfunction detection process of the moisturizing cap 363 is executed periodically or based on an instruction from the user.

As shown in FIG. 66, the control unit 6 as an example of the ejection state detection unit executes suction cleaning in step S1201 as in step S1002. Subsequently, in step S1202, the control unit 6 executes the ejection inspection process shown in FIG. 57 as in step S1003.

In step S1203, the controller 6 brings the moisturizing cap 93 into close contact with the head unit 35. That is, the controller 6 inputs a signal to the carriage motor driver 43 to move the carriage 32 and position the nozzle 110 so as to correspond to each cap 93. Further, the control unit 6 drives the capping motor 95 to rotate the rotary shaft 388 in the forward direction and raises the cap 93 to perform the capping operation.

In step S1204, the control unit 6 opens the moisturizing cap 93. That is, the control unit 6 drives the capping motor 95 to rotate the rotating shaft 388 in the opposite direction and lowers the cap 93.

In step S1205, the control unit 6 executes the ejection inspection process shown in FIG. 57 as in step S1003. Subsequently, in step S1206, the control unit 6 compares the inspection results of step S1202 and step S1205 similarly to step S1006, and determines whether or not air bubbles are mixed in the nozzle 110 or the cavity 141 as an example of the pressure chamber. To do. That is, when the bubbles in the nozzle 110 or the cavity 141 have not increased (step S1206: NO), the control unit 6 ends the malfunction detection process for the cap 93.

On the other hand, when the number of the cavities 141 in which the bubbles are mixed in the inspection of step S1205 is increased as compared with the number of the cavities 141 in which the bubbles are mixed in the inspection of step S1202 (step S1206). : YES), and moves the process to step S1207. Then, in step S1207, the control unit 6 causes the operation panel 7 as an example of the notification unit to display a message indicating that the moisturizing cap 93 needs to be replaced, and ends the malfunctioning detection process of the cap 93.

Next, the operation when detecting the malfunction of the moisturizing cap 93 will be described.
Now, in the printer 1, when suction cleaning is performed, bubbles and foreign matter are discharged together with the liquid from the nozzle 110 covered by the cap 92. After that, the state inside the cavity 141 is detected by performing a discharge inspection process. That is, the control unit 6 detects the vibration waveform of the cavity 141 before the capping operation.

Subsequently, the control unit 6 performs a capping operation of closing the space 263 exposed by the nozzle 110 with the cap 93 and separates the cap 93 from the head unit 35. At this time, if the atmosphere communication portion 384 of the moisturizing cap 363 is clogged, air may be pushed into the nozzle 110. Therefore, the control unit 6 performs the ejection inspection process after the capping operation, and when the bubbles in the cavity 141 increase, it is estimated that the bubbles are mixed with the capping.

In other words, the control unit 6 detects the vibration waveform of the cavity 141 before the cap 93 contacts the head unit 35 and closes the space 263 facing the nozzle 110. Further, the control unit 6 detects the vibration waveform of the cavity 141 after the cap 93 that closes the space 263 facing the nozzle 110 opens the sealed space 263. Then, when the change in the state inside the cavity 141 is an increase in bubbles inside the cavity 141, it is determined that the atmosphere communication unit 384 is malfunctioning. Then, the control unit 6 displays a message on the operation panel 7 to prompt replacement of the moisturizing cap 363.

According to the sixth embodiment, the following effects can be obtained in addition to the effects (1) to (12) of the fifth embodiment.
(13) When the change in the state inside the cavity 141 is an increase in bubbles, it can be inferred that bubbles are mixed from the nozzle 110 in accordance with the capping operation. Therefore, it can be determined that the moisturizing mechanism 361 that has performed the capping operation is malfunctioning.

(14) The atmosphere communicating portion 384 may not perform the function of communicating the closed space 263 closed by the cap 93 with the atmosphere due to, for example, the liquid adhering and solidifying. When the space 263 facing the nozzle 110 is sealed with the moisture retaining cap 363 having an insufficient function of the atmosphere communicating portion 384, the pressure in the sealed space 263 may increase and air may mix in from the nozzle 110. In that respect, the malfunction of the atmosphere communicating portion 384 is judged by detecting whether or not the bubbles are increasing before and after the cap 93 comes into contact with the head unit 35 and seals the space 263 facing the nozzle 110. can do.

The above embodiment may be modified as follows.
-As shown in FIG. 67, the control unit 6 may detect the state of the cavity 141 in a state where the closed space 263 facing the nozzle 110 is under negative pressure (modification). That is, the printer 1 includes a cap 92 as an example of a cap unit and a suction pump 94 as an example of a maintenance pump as the maintenance mechanism 72 (see FIG. 54) as an example of the maintenance unit. The maintenance mechanism 72 is a consumable item in which the function of sealing the space 263 facing the nozzle 110 deteriorates when the sealing performance of the cap 92 deteriorates due to deterioration over time, for example. In addition, when a tube pump is used as the suction pump 94, the restoring force of the tube may decrease due to deterioration over time, and the function of sucking the sealed space 263 may decrease.

Then, the suction cleaning operation may be performed as an example of the maintenance operation of the head unit 35 that drives the suction pump 94 by bringing the suction cap 92 into contact with the head unit 35. Further, the state inside the cavity 141 may be detected before the suction cleaning operation and during the suction cleaning operation.

That is, as shown in FIG. 67, when a negative pressure is applied to the closed space 263 facing the nozzle 110, the inside of the nozzle 110 and the cavity 141 communicating with the closed space 263 also have a negative pressure. Therefore, the diaphragm 121 is displaced in the direction of decreasing the volume of the cavity 141. Therefore, when the electrostatic actuator 120 is driven while the diaphragm 121 is deformed and the vibration waveform of the cavity 141 vibrated by the driving of the electrostatic actuator 120 is detected, the vibration detected when the diaphragm 121 is not deformed is detected. The waveform is different.

Therefore, as shown in FIG. 68, the control unit 6 first detects the vibration waveform of the cavity 141 in the state where the negative pressure before the suction cleaning operation is not applied.
Subsequently, as shown in FIG. 67, the control unit 6 detects the vibration waveform of the cavity 141 in the state where the negative pressure is applied during the suction cleaning operation. Further, the control unit 6 determines that the function of the maintenance mechanism 72 is normal when the state inside the cavity 141 changes before and during the suction cleaning operation.

In this way, when a negative pressure is applied to the closed space 263 closed by the cap 92, the negative pressure is also applied to the cavity 141 via the nozzle 110. Further, the vibration waveform of the cavity 141 changes depending on whether the negative pressure is applied to the cavity 141 or not. Therefore, when the state inside the cavity 141 is changed before the suction cleaning operation in which the negative pressure is not applied and during the suction cleaning operation in which the negative pressure is applied, the negative pressure is applied to the cavity 141. It can be determined that the maintenance mechanism 72 is functioning normally.

When detecting the vibration waveform of the cavity 141 during the suction cleaning operation as described above, a valve may be provided on the upstream side of the cavity 141 and the suction cleaning operation may be performed with the valve closed. That is, by providing the valve, it is possible to reduce the consumption of the liquid and to easily deform the diaphragm 121.

In the fifth embodiment, even if the cause of the discharge abnormality of the nozzle 110 is the inclusion of bubbles, the maintenance method may be changed depending on the position and the number of the discharge abnormality nozzles 110 detected. For example, when there are a large number of ejection abnormality nozzles 110 near each other due to the inclusion of bubbles, it is highly possible that relatively large bubbles are present and cannot be eliminated without suction cleaning. On the other hand, even if the bubbles are mixed in, when the number of the ejection abnormality nozzles 110 is small or when the ejection abnormal nozzles 110 are dispersed at positions distant from each other, relatively small bubbles exist near the nozzle 110. However, the bubbles can often be discharged by flushing. Therefore, when there are a certain number or more of ejection abnormality nozzles 110 due to the inclusion of air bubbles within a predetermined range, the maintenance operation is suspended, and suction cleaning is executed after the recording processing on the recording paper P is completed, If the abnormal ejection nozzles 110 are dispersed, the recording process may be interrupted and the flushing may be executed.

In the fifth embodiment, the ejection abnormality associated with the regular flushing is detected during the backward movement in the second scanning direction -X, and the detection cannot determine that the nozzle 110 is suspected of being ejection abnormality or the normal nozzle 110. If there are such nozzles 110, re-detection may be performed when these nozzles 110 are subject to the forward movement in the first scanning direction +X after the direction change at the end on the one-digit side. In this case, it is preferable to use the drive waveform for regular flushing in the first detection, and use the inspection waveform in the second detection. According to this configuration, the ejection failure nozzle can be reliably detected by the inspection waveform in the re-detection while appropriately performing the regular flushing.

In the fifth embodiment, the discharge abnormality associated with the regular flushing is detected during the backward movement in the second scanning direction −X, and the forward movement in the first scanning direction +X is performed after the direction is changed at the end on the one-digit side. In order to confirm whether or not the ejection abnormality of the nozzle 110 has been eliminated during the backward movement in the second scanning direction −X in the non-printing area NA on the one-digit side when flushing or wiping is performed during movement. Alternatively, the abnormal discharge may be detected again. This makes it possible to confirm whether or not the detected abnormal nozzle 110 has recovered to a normal state. Further, when the ejection abnormality nozzle 110 is detected again by the re-detection, flushing or wiping may be performed at the time of the next forward movement in the first scanning direction +X. As a result, it is possible to reliably suppress the occurrence of ejection abnormality in the subsequent printing operation.

In the fifth embodiment, when the pressure chamber 141 vibrates in association with the ejection operation of the liquid droplets on the recording paper P, the residual vibration is detected to detect the nozzle 110 having the ejection abnormality. Good. In this case, since it is possible to detect the ejection abnormality in the recording area PA, it is possible to quickly perform flushing or wiping as a maintenance operation when the recording area PA is moved to the non-recording area NA.

Alternatively, when there is a nozzle 110 that has detected a discharge abnormality associated with the discharge operation of the droplets on the recording paper P and cannot judge that the discharge abnormality is suspected or that the nozzle 110 is a normal nozzle 110, those nozzles 110 Alternatively, the ejection abnormality may be detected again at a position corresponding to the liquid receiving portion 73. According to this configuration, the droplet ejection operation is performed only on the nozzle 110 suspected of being abnormal, and the ejection abnormality detection unit 10 performs detection. Therefore, it is not necessary to eject an ink droplet from the nozzle 110 that was normal during the recording operation. .. Therefore, it is possible to avoid wasteful ejection of ink, and it is possible to reduce the amount of ink consumption. Further, the load on the discharge abnormality detecting unit 10 and the control unit 6 can be reduced.

In each of the above-described embodiments, the inspection waveform that does not eject the droplet to the nozzle 110 that does not eject the droplet during the recording process or the regular flushing (for example, the waveform (A) or the waveform (B) shown in FIG. 51). ) May be generated to detect the discharge abnormality. Even in the case of performing the detection without the ejection of the liquid droplets, it is preferable to perform the detection when the inkjet head 100 is arranged at a position corresponding to the liquid receiving portion 73. According to this configuration, even if droplets are accidentally ejected when the pressure chamber 141 is vibrated, the ejected droplets can be received by the liquid receiving portion 73, so that the recording paper P or Does not pollute the inside of the device.

In the fifth embodiment, a pressurizing mechanism for pressurizing and supplying the liquid is provided from the accommodating portion that stores the liquid ejected by the inkjet head 100, such as the ink cartridge that stores the ink, toward the inkjet head 100. Good. In this case, as the maintenance operation, the pressure cleaning in which the liquid is discharged from the nozzle 110 can be performed by driving the pressure mechanism. If the pressure cleaning is performed when the inkjet head 100 is arranged at a position corresponding to the liquid receiving portion 73, the recording sheet P and the inside of the apparatus are not polluted by the liquid discharged from the nozzles 110, which is preferable. .. Then, by the pressure cleaning, all the nozzles 110 can be cleaned at the same time, and the cleaning mechanism 91 may not be provided for cleaning. Alternatively, the pressure mechanism may be driven together with the suction cleaning to perform stronger cleaning.

Since the time required to execute the pressure cleaning is often longer than the threshold value Tng, it is preferable to suspend the execution during the recording process and to execute it after the recording process is completed. However, when the time required to execute the pressure cleaning or the suction cleaning is equal to or less than the threshold value Tng, the recording process may be interrupted and the cleaning operation may be performed.

In each of the above embodiments, the cleaning mechanism 91 may include a suction cap that surrounds all the nozzles 110 at the same time. According to this configuration, all the nozzles 110 can be cleaned with one suction cleaning, so that the time required for the maintenance operation is required even when the nozzles 110 with abnormal ejection exist over a plurality of nozzle rows 110N. Can be shortened.

When the cleaning mechanism 91 includes a suction cap that surrounds all the nozzles 110 at the same time, the ejection abnormality may be detected by ejecting a droplet toward the cap. In this case, since the cap functions as the liquid receiving portion, the flushing unit 74 may not be provided. Further, when the cleaning mechanism 91 includes a suction cap that surrounds all the nozzles 110 at the same time, the nozzle 110 can be prevented from being dried by capping the nozzles 110. Therefore, the moisturizing cap 93 is not required. Good.

In each of the above embodiments, the maintenance mechanism 72 may be arranged in the non-recording area NA on the 80th digit side, or the components of the maintenance mechanism 72 may be arranged in the non-recording area NA on both sides of the recording area PA. .. For example, a cleaning mechanism 91 having a suction cap capable of simultaneously surrounding all the nozzles 110 is arranged in the non-recording area NA on the 1st digit side, while a flushing unit 74 is arranged in the non-recording area NA on the 80th digit side. Good. According to this configuration, it is possible to detect the ejection abnormality associated with the ejection of the droplet in any of the non-recording areas NA.

-In the said 5th Embodiment, the wiping member 82 is not restricted to the strip|belt-shaped member which can absorb liquid. For example, a blade-shaped wiping member (wiping member) may be formed of an elastomer that does not absorb liquid, and the elastically deformable tip portion of the wiping member may be the wiping portion. However, it is preferable that the wiping member is a member capable of absorbing the liquid, because it is difficult for the liquid to be scattered to the surroundings with the wiping.

In each of the above embodiments, the means and method for detecting the discharge abnormality of the nozzle and the cause of the discharge abnormality in the droplet discharge device are the methods for detecting and analyzing the vibration pattern of the residual vibration of the diaphragm as described above. Not limited. The following are examples of changes in the method for detecting abnormal discharge. For example, there is a method in which an optical sensor such as a laser is directly irradiated and reflected on the ink meniscus in the nozzle, the vibration state of the meniscus is detected by a light receiving element, and the cause of clogging is specified from the vibration state.

Alternatively, the presence or absence of ejection abnormality is detected using a general optical dot dropout detection device that detects whether or not the flying droplets have entered the detection range of the sensor. Then, after the ejection operation, it is estimated that the ejection abnormality that occurs after a predetermined drying time that may cause missing dots has occurred due to drying, and regarding the ejection abnormality that occurs before the elapse of the drying time, There is a method of presuming that the cause is adhesion of foreign matter or mixing of air bubbles.

In addition, a vibration sensor is added to the above-mentioned optical dot dropout detection device, it is judged whether vibration that bubbles can be mixed is added before abnormal discharge occurs, and if such vibration is added, bubbles are mixed. There is a method of estimating that is the cause of the discharge abnormality.

Furthermore, the missing dot detection means need not be limited to the optical type, and for example, a heat-sensitive detection device that detects the temperature change of the heat-sensing unit by receiving the discharge of a droplet, or charging an ink droplet. A detection device that detects a change in the charge amount of the discharged and landed detection electrode or a capacitance-type detection device that changes when an ink droplet passes between the electrodes may be used. In addition, as a method of detecting the adherence of paper dust, a method of detecting the state of the nozzle surface as image information with a camera or the like, or by scanning an optical sensor such as a laser near the nozzle surface to detect the presence of paper dust A method of detecting it can be considered.

In the fifth embodiment described above, the ejection abnormality detection unit may detect at least the presence or absence of ejection abnormality in the nozzle 110, and does not necessarily detect the cause thereof. For example, when there are a certain number or more of nozzles 110 with abnormal discharge within a predetermined range, it is estimated that the inclusion of bubbles is the cause of abnormal discharge, and suction suction is selected as the maintenance operation, while the number of nozzles with abnormal discharge is set. If the numbers are less than or equal to a certain number or are distributed to each other, flushing or wiping may be selected as the maintenance operation.

In each of the above-described embodiments, the droplet discharge device does not include the carriage 32, but includes a long fixed droplet discharge unit that corresponds to the entire width (length in the main scanning direction) of the recording medium. You may change to a line type droplet discharge device. In this case, the droplet discharge unit may be arranged such that a plurality of unit head units having nozzles are arranged in parallel so that the printing range extends over the entire width of the recording paper P, or a single long head is used. By arranging a large number of nozzles so as to extend over the entire width of the recording paper P, the print range may be extended over the entire width of the recording paper P. Also in this case, the printing of one line by the droplet discharge unit and the intermittent transfer of the recording medium are alternately performed, so that a maintenance operation such as wiping is executed while the recording medium is transferred, for example. It is possible.

In the sixth and seventh embodiments described above, a piezoelectric element may be provided as an actuator that vibrates the cavity 141 as an example of the pressure chamber of the head unit 35, as in the second embodiment. Then, the control unit 6 may detect the state of the cavity 141 by detecting the vibration waveform of the cavity 141 vibrated by driving the piezoelectric element.

In the sixth and seventh embodiments, by detecting the vibration waveform of the cavity 141 before and after the maintenance operation, the filters 271-273 or the moisturizing cap 363 function when bubbles increase in one cavity 141. You may judge that it is insufficiency. Further, when the number of the cavities 141 in which air bubbles are mixed increases, it may be determined that the filters 271-273 or the moisturizing cap 363 are malfunctioning. Furthermore, when an increase in air bubbles in the cavity 141 can be confirmed in the cavity 141 having a threshold value (for example, 20%) or more, it may be determined that the filters 271-273 or the moisturizing cap 363 are malfunctioning. Alternatively, the vibration waveform of some of the cavities 141 may be detected, and the malfunction may be determined based on the detection result.

-In the said 6th Embodiment, when performing the clogging detection process of the filters 271-273, it is not necessary to compare the passage amount and a threshold amount. For example, when the clogging of the filters 271 to 273 is detected based on an instruction from the user, the ejection inspection process may be executed regardless of the passing amount.

In the sixth and seventh embodiments, the suction cleaning before the ejection inspection process may not be performed.
In the sixth embodiment, only the filters 271-273 may be replaceable with respect to the liquid supply passage 262.

-In the said 6th Embodiment, the filters 271-273 may differ in the collection capability. That is, a difference may be provided in the ease of clogging, and the replacement of the filters 271 to 273 may be prompted at different timings.

-In the said 6th Embodiment, the printer 1 should just be equipped with at least 1 of the filters 271-273. Further, the filters 271 to 273 can be arranged at arbitrary positions in the liquid supply passage 262. For example, the filter unit 268 may be provided between the pressure adjusting valve 269 and the head unit 35.

-In the said 6th Embodiment, the filters 271-273 may be arrange|positioned in the aspect which cannot be replaced|exchanged. That is, the filter unit 268, the pressure adjusting valve 269, and the head unit 35 may be provided in the liquid supply passage 262 in a non-detachable manner. Further, in the seventh embodiment, the moisturizing mechanism 361 may be arranged in a non-replaceable manner.

-In the said 6th Embodiment, the printer 1 does not need to be equipped with a filter. Further, malfunction of the maintenance mechanism 72 as an example of the maintenance unit may be detected. That is, the maintenance mechanism 72 includes a cap 92 as an example of a cap portion and an atmosphere release valve 264 as an example of an atmosphere communicating portion. Then, the control unit 6 causes the maintenance mechanism 72 to perform the capping operation of the head unit 35 by the cap 92 with the atmosphere opening valve 264 opened as a maintenance operation, and detects the vibration waveform of the cavity 141 before and after the capping operation. You may. That is, similarly to the moisturizing cap 93, when the air bubbles in the cavity 141 increase after the capping operation, it is possible to determine that the atmosphere release valve 264 is malfunctioning, like the suction cap 92.

In the sixth embodiment and the seventh embodiment, the notification unit may be a device that emits sound or light to prompt replacement, and may be provided separately from the printer 1. For example, the host computer 8 may be used as a notification unit to display a message or a drawing that prompts replacement. Also, the notification unit may not be provided.

In each of the above-described embodiments, the vibration waveform of the cavity 141 may be detected by a mechanism other than an actuator that vibrates the cavity 141 to eject liquid droplets from the nozzle 110. That is, as in the third embodiment, for example, the heating element 450 for ejecting droplets from the nozzle 110 and the electrode 462 for detecting the vibration waveform of the cavity 141 may be separately provided.

In the sixth embodiment, the ejection amount per unit time ejected from the nozzle 110 in accordance with the flushing operation may be different from the maximum amount ejected from the nozzle 110 per unit time during the recording process. That is, for example, the amount that can be supplied to the nozzle 110 per unit time is made larger than the maximum amount that is discharged per unit time during the recording process, and the flushing operation is performed so that the maximum amount that can be supplied is discharged. Good. Further, the flushing operation may be performed so as to discharge the maximum required supply amount to obtain the required recording quality.

In each of the above-described embodiments, the ejection target liquid (droplet) ejected from the droplet ejection unit (the inkjet head 100 in the above-described embodiments) of the droplet ejection device is not limited to ink. A liquid (including a dispersion liquid such as a suspension or an emulsion) containing the above material can be used. That is, a filter material of a color filter, a light emitting material for forming an EL light emitting layer in an organic EL (electroluminescence) device, a fluorescent material for forming a phosphor on an electrode in an electron emitting device, a PDP (plasma display panel). For forming a fluorescent material for forming a phosphor in the device, a moving material for forming a moving body in the electrophoretic display device, a bank material for forming a bank on the surface of the substrate W, various coating materials, and forming electrodes. Liquid electrode material, particle material forming spacers for forming a small cell gap between two substrates, liquid metal material for forming metal wiring, lens material for forming microlenses, resist material, Examples thereof include a light diffusion material for forming a light diffuser and various test liquid materials used for biosensors such as a DNA chip and a protein chip.

In each of the above-described embodiments, the recording medium (droplet receiving material) to which droplets are ejected is not limited to paper such as recording paper, but other media such as films, woven fabrics, non-woven fabrics, and glass substrates. It may be a work such as various substrates such as a silicon substrate.

DESCRIPTION OF SYMBOLS 1... Printer (an example of a droplet discharge device), 6... Control part (an example of an ejection state detection part), 7... Operation panel (an example of a notification part), 31... Ink cartridge (an example of a liquid supply source), 35... Head unit (an example of a droplet discharge part), 72... Maintenance mechanism (an example of a maintenance part), 92... Cap (an example of a cap part), 93... Cap (an example of a cap part), 94... Suction pump (of a maintenance pump) 110) Nozzle, 120... Electrostatic actuator (example of actuator, example of maintenance part), 141... Cavity (example of pressure chamber), 262... Liquid supply path, 263... Space, 264... Atmosphere release valve (atmosphere) 271 to 273... Filter (example of functional part), 361... Moisture retention mechanism (example of maintenance part), 363... Moisture retention cap, 384... Atmosphere communication part, P... Recording paper (example of medium).

Claims (9)

A droplet discharge unit that has a plurality of nozzles that discharge the liquid supplied from the liquid supply source through the liquid supply path as droplets, and that performs recording processing by discharging droplets from the nozzles onto the medium;
A maintenance unit that performs a maintenance operation of the droplet discharge unit;
A discharge state detection unit capable of detecting a discharge state in the nozzle,
Equipped with
The discharge state detection unit detects the discharge state before the maintenance operation and at least one of during the maintenance operation and after the maintenance operation, and based on a change in the discharge state due to the maintenance operation, the maintenance unit And a malfunction of at least one of the functional units arranged in the liquid supply path can be determined. The liquid according to claim 1, wherein when it is determined that the change in the discharge state is due to an increase in bubbles, it is determined that at least one of the maintenance unit and the functional unit is malfunctioning. Drop discharge device. The maintenance unit includes a moisturizing cap that includes a cap unit that contacts the droplet discharge unit and closes a space facing the nozzle, and an atmosphere communication unit that communicates the space with the atmosphere. Block the space in the cap part,
The discharge state detection unit detects the discharge state before the cap unit closes the space and after the cap unit that closes the space opens the space, and a change in the discharge state is caused by a bubble. The droplet discharge device according to claim 2, wherein when it is determined that the increase is due to an increase, it is determined that the atmosphere communication unit is malfunctioning. The functional unit includes a filter arranged in the liquid supply path to collect foreign matter,
The maintenance section discharges the liquid from the nozzle as the maintenance operation,
The filter is determined to be clogged when it is determined that the change in the discharge state detected before and after the maintenance operation is due to an increase in bubbles. Droplet ejection device. The maintenance unit is configured to perform the maintenance operation such that the ejection amount per unit time from the nozzle is equal to the maximum ejection amount per unit time from the nozzle during the recording process. The liquid droplet ejection apparatus according to claim 4, which ejects a liquid. The maintenance unit includes a cap unit that contacts the droplet discharge unit and closes a space facing the nozzle, and a maintenance pump that discharges the liquid from the nozzle by applying a negative pressure to the space. A negative pressure is applied to the space closed as the maintenance operation,
The liquid droplet ejecting apparatus according to claim 1, wherein when the ejection state detected before the maintenance operation and during the maintenance operation changes, the function of the maintenance unit is determined to be normal. The discharge state detection unit detects the discharge state by detecting a vibration waveform of the pressure chamber vibrated by driving an actuator that vibrates a pressure chamber communicating with the nozzle. The droplet discharge device according to claim 6. The droplet discharge device according to claim 7, wherein the droplet discharge section discharges droplets from the nozzle by driving the actuator to vibrate the pressure chamber. 9. The notification unit prompts replacement when the malfunction of at least one of the maintenance unit and the functional unit is determined based on the change in the discharge state. The droplet discharge device according to one item.